look up any word, like turnt:
 
1.
When another man has sexual relations with your girlfriend, or partner. Usually refers to when another guy hooks up with your girl.
Man, Fred's been out of town for the past two weeks, and word on the street is that some other nigga crept on his girl last night.
by Ellis Burks July 10, 2008
 
2.
To jump, ambush or beat somebody down.
Check yo self nigga 'fore you get yo ass crept on!!
by MF SPOCK March 22, 2007