When one walks down the street, usually drunk, and urinates as he walks (usually for the amusement of his buddies/mates). The true walking piss is done without the aid of hands, a feat that is perfectly feasible as long as one isn't hung like a field mouse. Extra points are earned if the individual doing the walking piss executes it in an area in which pedestrians are present. The general rule of the walking piss amongst pedestrians is that if YOU don't look down at your dick, nobody else will either.
Yo, check out Chewy- he's gonna rip a walking piss right by that outdoor café .