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The female equivalent of duck butter. i.e. When the sweat from the butt and the vagina meet in the girlie-taint and form a spreadable buttery substance.
EEWWW! That bitch had so much swan margarine she could butter both halves of the bagel.

It is so good it will have you saying, "I can't believe its not duck butter!"
by butterbeard March 16, 2009
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