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The conglomeration of greasy substance that builds up between the ass cheeks after a particularly long day and resembles the smell of a shart. Occurs most often after it has been greater than 8 hours since a shower and is one of the substances to be removed whilst participating in a hooker shower.
"Girl, I had so much knap butter in my crack last night my thong was greasy!"
by shuddddders October 07, 2009
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