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I Don't Even Fucking Know.

Usually said when your really do not fucking know.

AIMPerson1: Dude, where do I stick my penis into her?

AIMPerson2: Bro, IDEFK.
by LFJoooooonnnneeeessss September 21, 2008
I don't even fucking know. This can be used when you just have sheerly not the slightest idea what the answer to a question or problem is.
boy: "Wtf is free running?"
girl: "Oh god. Idefk."
*girl goes on and attempts to explain it.*
by lovesonic April 02, 2010