Internet message acronym for "Make Up Your Fucking Mind". Used when confronting ambivalence or indecision in an IM or message forum.
1. She said she wants me, but won't let me take her on a date. Damn, girl, MUYFM.

2. Guy 1: "...And that's why your opinion of Cloverfield is wrong."
Guy 2: "WTF? You just agreed that JJ Abrams can't tell a whole story, and agreed that Cloverfield was weak as a picture overall. Then you say I'M wrong? MUYFM."
by Cicero's Assassin July 19, 2008
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