The burning itch you get in your thighs after you go jogging. Usually caused by the constant flapping of your flab, hence the name "flab itch".

The more you jog, the less flab. The less flab, the less itch.
Guy: Dude, ahh, what the hell. My thighs itch like hell! It's all red, too!
Guy #2: You just went jogging right? Probably flab itch.
by illEATurHARTout May 24, 2005
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