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to fill up your ass with air and slap someone with it letting out a fart in the process
shane dawson said it

dude she got whoopie slapped
by idonthaveapseudonym.0 January 11, 2011
When you fill your butthole with air, slap someone with it and a small poo comes out.
Dude if you don't shut up I'm gonna whoopieslap yo' ass
by ShadowNam January 10, 2011