Flirt and try to get out of there.

Figuring you wouldn’t dare be to harsh with a flirty naked hot slut if it was you. You smile sweetly and say. “Umm, actually I accidentally walked into the men’s room by mistake and some big hunk took that as an invite to fuck me raw.” You saunter up to him as sexy as you can and rub him lightly on the arm. “But he wasn’t nearly as sexy as you. How about you just let me go back to the party and I could make it worth your while.”

He seems to mull it over in his mind before answering.