Cat Skull
A sexual move where two males (preferably homeless or train-hoppers) simultaneously ejaculate on a the face of someone who is celebrating his/her birthday. The two males then draw whiskers on the face of the receiver and use the ejaculate as hair gel to make cat ears.
My friend's sister came to a party once with two friends. Apparently, all three of them are train-hoppers. They proceeded to give a friend a cat skull for his birthday, ate all of his birthday cake (with their hands) and left dirty hand prints all over the walls.