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1.
Butt Fucking Butt Buddies.

A much more intimate form of the relationship between butt buddies. BFBBs are intense in their time together and seem "inseparable" in more ways than one.
Person 1: "Did you see those two bros?"

Person 2: "They're totally BFBBs, the way play slap-ass so profusely"
by RedClamz June 19, 2010