1.    To cheat on your significant other.
Ex:    "Did you hear about Tyrone and Lisa? They split up cuz she caught him creepin."

2.    To give someone an awful or uncomfortable feeling.
Ex:    That dude's webbed fingers totally creep me out.

3.    A weird or perverse person.
Ex:    "I caught your neighbor looking at my girls butt man!" "Oh you mean Mr. Rodgers, everyone knows hes a creep."