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1. When you wear flannel boxers in the summer and your ass crack sweats.

2. When someone spreads a healthy portion of mayonaise in your ass crack.
It is 95 degrees out and Carl's got some serious mayobutt goin' on.
by Andrew January 13, 2005
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2
when you have a huge jiggly ass. similar to having eaten too much mayonnaise and having it go straight to your ass.

move that ass woman.
look at that boatload on her ass--talk about mayo butt.
by mayobutt November 06, 2009
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