A word used to insult or title someone idiotic, douche bag-esque or disliked for any reason.
"You're a muff!"

"What a muff!"

"That kid is such a muff"
by Malcom Little March 9, 2008
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Frank had a Muff that night he was drunk! Ha!
by Matt Prather February 21, 2006
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When someone says or does something stupid you apply the MUFF. Can also be applied via a braced MUFF. Taking your index finger and middle finger putting them together and applying pressure behind the idiots ear(just along the hair line) and pulling/swiping towards yourself catching they're ear. And hopefully achieving a snap noise and a disgruntled look of confusion from the receiver of the MUFF.
Guy: I think Larry the Cable guy is fricken hilarious...
Friend of Guy: Holy shit dude. I think you got a MUFF comin...
Guy: What? He's really funny.

Friend of Guy: Applies his index and middle fingers behind Guy's ear and swipes that shit... Achieving a loud snap sound.

(Guy then realizes he was being an idiot and apologizes for saying Larry the Cable Guy is hilarious.)
by Johnny Reds February 16, 2009
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1. A warm, furry place to warm up your appendages. 2. My girlfriend's cat.
"She has a might nice muff in her lap."
by Anonymous December 5, 2002
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