1. A way to shorten the phrase whats up. When your saying hello to a lass, its easy to say whayup rather than whats up.
2. A verb to express either jizzing, shitting, or anything that involves domination.
1. Bobby: Oh hey Jennifer, whayup!
Jennifer: Not alot Bobby, how are you.
Guy 1: Bro I just whayuped all over Stephanie's face after she gave me head.
Guy 2: Dude, that's whayup.