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1.
An action involving a larger woman and a man's genital regions.

A flab wank involves literal wanking off using two layers of fat around the penis.
" All that girl's good for is a flab wank"

" I wouldn't want a flab wank from her"
and...

" her datin add said skinny white female, you know what online dating is like though; thank god she could give a good old flab wank."
by Cap'n Higgins April 20, 2010