The roll of fat that forms on the back of a middle aged friend. This object is usually a surprise if you have not seen the guy in a number of years. The flab tends to look like a "flap", that if opened, might have the ability to absorb a double cheesburger (much like the Venus Flytrap). Although embarrassed, the friend knows that since he has "given up", no possibility for losing the flap exists.
Woah, Dude! Put your shirt back on...your Back Flap is freaking me out.

Hey Hans, does your Back Flap need a bra.

Buddy, what happened to you? You are sportin' a Back Flap?
by Gassner April 12, 2007
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