1 definition by cmsjds

Top Definition
n. - Acronym, standing for RANDOM FUCKING BONER. Used in reference to the erection one gets at the most impromtu of times, such as while sitting in a lecture about the holocaust, or while watching your sister's birth video. It never makes sense, but it happens nevertheless.
Dude, I was sitting in church during the Easter mass, and right when I went for communion, I had the world's hardest RFB! And I was wearing DRESS PANTS! ...I think Father Frank was getting an idea....
by cmsjds April 27, 2006
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