1 definition by 240490

A pair of trousers (usually an old pair of jogging bottoms with an elastic waistband) in which a male can comfortably masturbate whilst wearing, thus creating warmth on a cold night without the need for a duvet or blanket.

Called fap slacks across the Atlantic.
"I see mikes got his wank slacks on, guess we know what he'll be doing later!"
by 240490 September 21, 2012
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