A Dirty Nicholas is when you fuck a chick at the top of the stairs and then ride her down the stairs like a toboggan with your dick still in her. Note: the stairs must be carpeted and the carpet must be white.
I gave that bitch a dirty nicholas and now I have to pay to have her nose fixed and her carpet cleaned.
Girl friend: Oh baby, you feel sooo good, i feel like im in heaven
Boyfriend: oh yeah, now you'll get to see your mom again
Girlfriend: not another dirty Nicholas
Like dirty sanchez, but with menstrual blood instead of poo: after having sex during a girl's period, the man rubs his penis on her upper lip, leaving a red moustache.