wank slacks 

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!"

wank slacks by 240490 September 21, 2012