1 definition by Jumpin' JC

An abbreviation of the term "Gangsta Rap Made Me Do It", originating from Ice Cube's song of the same name. It essentially means "My bad, it wasn't my fault."
Paul: Ow! Why'd you slap me with your cock, then call me gay?
Jim: GRMMDI, dude.
Paul: Oh. We cool.
by Jumpin' JC August 25, 2010
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