The act of two men having sex at the same time with a hideously ugly woman. A variation of a threesome, it only becomes a pork roast if the girl is a complete munter. Often, the ritual of a Pork Roast is ended by throwing the girl's jeans out of the window, completing her humiliation.
"I slipped it up her arse while she sucked my mate off... afterwards we got rid of her by chucking her jeans out the window. Man that was a pork roast I'll never forget."