When someone fills their butthole full of air and then they slap somebody with it and let out a poo.
My boyfriend decided to try a new move on me called a whoopi slap. It was so gross.
Where you fill your ass with a bunch of air, then slap your freind releasing what is a so called "Whoopie Slap" or a massive fart.
DUDE! Did you hear that Whoopie Slap?