The goalkeeper has denied reports of an ongoing conflict between him and the Portugal international, while talking about the various relationships between players at the club
There has been persistent talk of internal problems at the Santiago Bernabue this season, particularly between the goalkeeper and Portugal international.
However, Casillas has moved to deny the latest reports while insisting that the Blancos squad is very much united.
"A holiday with Ronaldo? Of course I would go with him... and expenses paid," he told La Sexta Deportes.
"Cristiano, Pepe and [Fabio] Coentrao spend a lot of time together, they go together when on international duty with Portugal but when they come to Madrid they do like to hang amongst themselves.
"Marcelo is the joy of the team, while Mesut Ozil is very short and never wants to talk. I scolded him at first and I nicknamed him 'bream'. [Sami] Khedira is much the same though and it has not stopped [Sergio] Ramos from talking alot with Ozil.
"My team-mates call me melon now because my head is so much bigger than my body and it has just stayed."
The 31-year-old also commented on Karim Benzema's unusual fashion sense while explaining why he is never too critical of the media despite their constant hounding of him.
"The underpants of Benzema are so glamourous. They certainly grab your attention, They have many colours and do not pass unnoticed. Karim is a brave guy in regard to this," he continued.
"You have to pay a toll as a public figure. You have to understand why people are always taking photos because it is their profession, they also have to live."