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Bebe had only just joined Vitoria de Guimaraes from Estrela on a free transfer and had yet to even make a competitive appearance for the Primeira Liga club when Manchester United signed the 20-year-old for €9m in August 2010.
It was a truly baffling deal, not least because Red Devils boss Alex Ferguson had never even seen the forward play, admitting that he sanctioned the signing solely on the advice of former assistant manager Carlos Queiroz.
The move did not work out for either the club or the player, as Bebe departed Old Trafford in 2014 for Benfica, after three loan moves and just two Premier League appearances.
United received €3m for his services but that still represented a loss of €6m, as it was revealed that the English side had paid a total of €9m for Bebe, a third of which was pocketed by Jorge Mendes, who hadn't even been the attacker's agent at the time of the transfer.
Following the sale of Munir El Haddadi to Sevilla, it was clear that Barcelona needed another attacker. It was also widely known that the Catalans didn't have much money to spend.
In that context, it was hardly surprising that Barca decided to bring in a replacement on loan. What was shocking, though, was that they went for Kevin-Prince Boateng, with a view to a permanent transfer for €8 million (£7m/$9m) in the summer.
Now 31, the former AC Milan forward had been plying his trade at Sassuolo when he received the most unexpected of calls from Camp Nou on Monday.
In fairness, Boateng has impressed as a 'false 9' this season but his transfer has still taken Blaugrana fans by surprise, given he netted just four times during the first half of the Serie A season.
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Sol Campbell learned the hard way that if something seems to good to be true, it probably is. The centre-back couldn't believe his luck when, in 2009, he was offered the most lucrative contract of his career (£40,000 per week) to join League Two side Notts County.
Director of Football Sven-Goran Eriksson had played a major role in convincing Campbell that the club's owners had sufficient funds to take the oldest club in football into the Premier League.
However, Campbell realised after one game that they didn't even have the money to pay his wages, so he departed, with early reports claiming that he was not in good enough shape to play for County.
In truth, though, the former England international was disgusted with himself, later revealing that he had been "a mug" to have believed everything he had been told by Eriksson, executive chairman Peter Trembling and Munto Finance, a Middle Eastern consortium owned by Qadbak Investments, had told him.
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Scottish football fans and journalists thought that Ivano Bonetti was talking pure guff when he announced in September 2000: "My aim is to bring Claudio Caniggia to Dens Park."
However, a matter of weeks later, the Dundee boss achieved his goal, signing one of the stars of the 1990 World Cup on a short-term contract.
“I intend to do well for the club and I hope I can repay the faith they have shown in me," the forward declared on the day of his unveiling, and he proved a man of his word.
Indeed, Caniggia performed so well that he earned himself a move to Scottish Premier League giants Rangers, with whom he won five trophies.
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Andy Carroll's move to Liverpool is widely regarded as one of the strangest transfers of all time, primarily because of Reds chairman John W Henry's bizarre method of valuation.
Essentially, the American and his associates decided that the Reds would pay £15m less than whatever Chelsea gave them for outgoing forward Fernando Torres. The Blues offered a British-record £50m, so Liverpool duly paid Newcastle £35m for Carroll.
That was truly remarkable, for two reasons. Firstly, Carroll was coming off the back of one good half-season of Premier League football. Secondly, he didn't want to move to Anfield.
"I wasn't ready to leave," he subsequently admitted. "It came as a shock. Newcastle was my club. I was 22. I could never get a grip at Liverpool."
Indeed, Carroll didn't even know who his new team-mates would be, revealing that he had to Google Liverpool's squad on the helicopter ride down to Merseyside.
Injuries consistently ruined the striker's hopes of striking up a real understanding with fellow new arrival Luis Suarez but the unavoidable truth is that £35m proved a huge waste of money for Carroll, who hit just six Premier League goals in three years at Anfield.
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With his first job in management, at Preston North End, having ended in acrimonious circumstances, Manchester United and England legend Bobby Charlton decided to resume his playing career.
While that was somewhat surprising, given he was 38 at the time, what was truly shocking was that Charlton elected to do so in the League of Ireland with Waterford United.
Despite his age, the World Cup winner impressed every time he set foot on the field. Unfortunately, the convoluted payment scheme that Waterford had agreed with Charlton, which involved a percentage of gate receipts, quickly proved utterly unsustainable and the midfield returned to England having played just four games for the Irish club.
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In November 1996, Southampton boss Graeme Souness received a phone call from a man claiming to be Ballon d'Or winner George Weah, who advised the Scot to sign his cousin, Ali Dia. Incredibly, Souness handed the unknown striker a one-month contact.
Dia was meant to make his debut in a reserve team game against Arsenal but the match was postponed due to a waterlogged pitch. As a result, Souness instead elected to throw him in at the deep end, bringing Dia on as a substitute in a Premier League game against Leeds on November 23, 1996. It did not go well.
"He ran around the pitch like Bambi on ice," said Southampton legend Matthew Le Tissier. "It was very embarrassing to watch."
Dia was released 14 days into his contract and it was later revealed that the Senegalese had absolutely no connection whatsoever to Weah, who had been so 'expertly' impersonated by one of Dia's friends.
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Thomas Gravesen was undeniably a strange one but the most bizarre signing in Real Madrid's history was undoubtedly that of Julien Faubert.
Indeed, the entire football world was stunned when Los Blancos took the winger/full-back on loan from West Ham just before the close of the 2009 January transfer window.
There was an option to buy included in the deal but it was never taken up, not least because Faubert missed one training session as he mistakenly thought he had the day off, not to mention the fact he also appeared to nod off during a game against Villarreal.
The Frenchman denied doing so – “I didn’t fall asleep on the bench; I prefer beds” – but it adequately summed up the rather dream-like absurdity of his short spell in the Spanish capital.
Jay Bothroyd once said of Al-Saadi Gaddafi: "His dad is obviously a tyrant and he dictated over his countrymen through fear but Saadi was never like that. He was always friendly and polite."
However, even Bothroyd admitted that the man who paid for his honeymoon "wasn't the best" footballer. Despite that, Gaddafi was, alongside Bothroyd, one of Perugia's new signings for the 2003-04 season.
Of course, it was a purely political move, with then Italian Prime Minister electoral candidate (and AC Milan owner) Silvio Berlusconi telling the Umbrian club's president, the infamous Luciano Gaucci, that signing the son of Colonel Muammar Gaddafi would be good for the country's relationship with Libya.
Having previously spent his time playing exclusively in his homeland, Al-Saadi employed the services of noted sportsmen Diego Maradona and Ben Johnson to help him prepare for the rigours of Serie A, so it came as quite the shock when he tested positive for nandrolone before he had even made a single league appearance...
Remarkably, he returned from his ban to belatedly make his debut before the season was out, against Juventus of all teams, and even saw a further 11 minutes of action with Udinese before eventually giving up on his dream of making it as a footballer after a short, equally unsuccessful stint with Sampdoria.
When Sven-Goran Eriksson left Lazio to take charge of England, his still-playing assistant Roberto Mancini received several offers to continue his playing career in Serie A.
However, the 36-year-old stunned all and sundry by electing to join Leicester City. Everyone at Filbert Street was enthused by the arrival of the gifted No.10, who had won the European Cup with Sampdoria in 1992.
"Everyone thinks the world of Robbie because he is such a star in Italy," revealed Foxes manager Peter Taylor. "Muzzy Izzet said he would move out of his mansion, let Robbie move in there and he would go and live in a caravan!"
Unfortunately, permanent lodgings were not required, as Mancini never settled in Leicester and featured in just five games before returning to Italy to take on his first coaching role, at Fiorentina.
Javier Mascherano & Carlos Tevez
In the summer of 2006, Carlos Tevez and Javier Mascherano were two of the most in-demand players in world football, having helped Corinthians win the Brasileiro Serie A title the year before.
Barcelona, Real Madrid and Juventus were all linked with the Argentine duo. So, there was widespread disbelief when they joined Premier League strugglers West Ham United.
The nature of the deal was immediately queried, with reports suggesting that third parties had been involved in the transfer, but both were ultimately cleared to play for the London outfit.
West Ham were eventually fined £5.5m for breaching Premier League rules over the double-deal but allowed to continue fielding their star duo and, on the final day of the season, Tevez scored the goal that saw the club avoid relegation.
In a wholly unsurprising development, though, both Tevez and Mascherano left Upton Park that summer, with the forward moving to Manchester United and the midfielder joining Liverpool.
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After being released by Middlesbrough in 1999, at the age of 20, Ronnie O'Brien feared that he might end up back working in a supermarket. Instead, the Irishman was snapped up on a free transfer by Juventus in one of the most incredible turn of events the game has ever seen.
O'Brien failed to follow in the footsteps of compatriot Liam Brady by becoming a Bianconeri legend, although he was voted Time Magazine's 'Man of the Century' by mischievous Irish football fans, only for the famous publication to remove his name from the online poll.
Furthermore, while his spell with Juve did not work out, O'Brien carved out quite the career for himself in the United States, earning inclusion in the MLS All-Star team four years in a row between 2004 and 2007.
Diego Maradona's world-record move from Boca Juniors to Barcelona in 1982 created huge excitement in Catalunya. However, Allan Simonsen was less than impressed by the Argentine's arrival.
At the time, Primera Division sides could only field two foreign players and given Bernd Schuster was the Blaugrana's star midfielder, Simonsen realised that his game time would be severely limited by the addition of the most expensive player of all time.
Real Madrid and Tottenham Hotspur led the chase for the Denmark international, who had beaten Kevin Keegan and Johan Cruyff to the Ballon d'Or just five years previously, but English Second Division side Charlton sent shockwaves through the footballing world by offering £324,000 for him.
Barca, unsurprisingly, accepted the offer (though they demanded half of the fee up front as they were, correctly, suspicious about where the money was coming from) but it was a shock when Simonsen agreed to the move too.
However, the striker was apparently drawn to the idea of playing in a less pressurised environment and he scored nine times in 16 appearances for Charlton before, almost inevitably, the club found themselves in financial difficulty, unable to pay the record signing's wages, thus allowing him to return to Denmark to join Vejle BK.
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In arguably the most sensational return in football history, Brazil legend Socrates revealed that he was coming out of retirement in 2004, at the age of 50 – to sign for Garforth Town.
The non-league club's owner and manager, Simon Clifford, had connections with Brazil through his Socatots coaching schools but it was still a truly unbelievable story.
"I put out a few feelers and Socrates said he would be interested," Clifford explained. "He's a pretty principled guy and isn't interested in the money - which is just as well because we're not paying him."
In the end, Socrates, the captain of the wonderful Brazil side that had lit up the 1982 World Cup, only made one, 12-minute substitute appearance for Garforth, admitting that his chain-smoking, coupled with the bitterly cold Yorkshire weather, put paid to any hopes he had of making a real impact in England.
Not much went right for Victor Valdes after deciding to walk away from Barcelona. The three-time Champions League winner suffered ligament damage at the tail end of his final season at Camp Nou, in 2013-14, prompting Monaco to pull out of an agreement to sign the goalkeeper.
Manchester United eventually came to his rescue but Valdes quickly fell out with then manager Louis van Gaal and, in his desperate search for game time, he joined Standard Liege on loan in January 2016.
It was quite the fall from grace for a man who had been playing in front of 90,000 people at Camp Nou just two years before and, although he got his hands on the Belgian Cup, further ignominy followed when Valdes' spell with Standard was cut short following the club's decision to release him in order to create more space for younger players.
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Quite why Real Madrid thought it would be a good idea to sign Jonathan Woodgate is anyone's guess. True, the Englishman was a quality defender on his day but those days were few and far between because he was rarely fully fit.
Indeed, he was even injured when Real made their move, in 2004. With that in mind, one would have assumed that the Spanish side would have at least subjected Woodgate to a thorough medical. And yet the club's doctors failed to detect a thigh problem that kept the centre-back out for a year.
When he was finally available for selection, Woodgate endured arguably the worst debut in history. "I thought: 'Right, you're back. Show them what you can do,'" he later recalled of his appearance in a Liga game against Athletic Bilbao.
But he scored an own goal and was sent off. A forgiving Bernabeu gave him a standing ovation nonetheless but nobody complained when Woodgate was sent back to England in 2006 after just eight further Liga outings.