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1.
Acronym for 'Get Raped By Marianne' or 'Get Raped By Math'

Marianne is a mythical creature from the underworld who's instrument of destruction is a pencil.

Math in this instance relates to college classes such as physics, 3D vectors and calculus.
Hey kyle, did you GRBM last night? I see you are walking a bit funny.
by DiafingDiafers August 27, 2010