You feel a surprise come from your a hole (you farted) and it rumbles your nut sac and everything inside your nut sac.

The action of the fart or gas (queef if your a fag), rumbles (shakes or moves) your gens (balls).
Yo dude I just had a "gens rumbler". You smell that?

Oh shit man you smell that, you been rumblin those gens or what???

Drew: Gens Rummmmmbler!

Walt: Fuck you man (He gets off the couch and leaves the room)
by Whale Dick May 5, 2009
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