Top definition
(1) An enthusiastic but insane person.

(2) One who is charismatic and engaging, but mentally incontinent.

(3) An aggressively foolish person.
He thinks that just because his roommate didn't clean up his belongings, he's justified in throwing them all in the trash! He's a "grade A nut"!
by BtotheBrown December 03, 2011
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