The small folded opening which is found in men's Y-fronts which enables the wearer to urinate without pulling down his underwear.
"Sorry about that vicar. I believe the explosion was caused by your candle igniting a small pocket of fart which had become temporarily trapped in the piss hatch of my trollies..."(etc)
by Bonny lad November 11, 2004
Get the Piss Hatchmug.