Ok, so I must know about a kazillion songs about sex but I can't think of any right now...
Ohhh,
Boner by the Secretions which is about this guy telling a girl how he wants to have sex with her
Blood, Sex and Booze - Green Day
Vanilla Sex - NoFX (I think)
Ummm...Damn there's so many. Oh well, I'll see if I can think of any more later.