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.
afterdick is the persistence of a sensation of flavor after the stimulating member has passed out of contact with the sensory end organs. The term is particularly used in relation to another dick that has been there before you.
Your friend had sex with said girl. You have sex with the same said girl, now you have had some afterdick. Afterdick only applies when you know the last person she sleep with.