the piss used to clear the penal shaft of cum or shit after sex or jerking off. a woman may use the same method after a deposit in her forward hole.
during the afterpiss I hit the toilet tank with a cum/piss mixture due to a semi and the fact it took a moment to figure the combination pressure-to-backsteps ratio needed to ark the fluid into the bowl.
when u go pee and after u already put it back in your pants it decides to trickle a little more out. leaving small wet spot on your pants that quickly evaparate.