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A sponge butt is a big ass butt that soaks up a fuckton of shit and provides amble padding for extended periods of sitting. Also, may produce thunder like farting
My mom has a hell of a sponge butt
by Syralee February 20, 2017
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Squidward: damn sponge they may call you SquarePants but you got a bubblebutt
SpongeBob: Only my main sister Patrick gets to look at my Spongebutt you pervert
by Adam Daire Martin October 28, 2019
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