The sex in Slaughterhouse-Five isn't very sexy. We know that people are having it, but it is never described very intensely. Still, there is a fair amount. Billy Pilgrim cheats on his wife in the laundry room of a friend's house during a party in Chapter 2, Section 29. We get a pretty clinical description of Billy impregnating Valencia in Chapter 5, Section 46. And Billy dreams about porn star Montana Wildhack (his partner in the Tralfamadorian zoo) in Chapter 5, Section 65. Billy also visits a pornographic bookstore in Chapter 9, among other scattered references to sex. So there is plenty of sex in Slaughterhouse-Five, but it's not a central theme.