Well this is sort of interesting, details found in the recent GTA IV BBFC classification report reveal that the game not only includes sexual references, prostitution, and lap dancing, but also portrayed masturbation.
“During gameplay the character can pick up prostitutes… What follows is an un-detailed portrayal of masturbation, fellatio and intercourse.”
“Sex references also occur during cut scenes, including references to strong sexual behaviour,” states the BBFC classification. “During gameplay the character can pick up prostitutes… “
“What follows is an un-detailed portrayal of masturbation, fellatio and intercourse. The character can also visit lap dancing clubs and request a private dance. While the game contains sexualised dancing and the portrayal of sex, there is no sexualised nudity.”
Via Videogamer.com