The act in which the male participant urinates directly into his female counterparts mouth, which she is not allowed to swallow. He then proceeds to face-fuck her in her urine filled mouth, with the ferocity of an automobile piston. This ideally occurs while the man is wearing a Chauncey Billups jersey.
Optional: When urinating in her mouth, go for the "3 point shot" by taking a few steps backwards for extra distance and accuracy (just like Chauncey).
Sarah: How was the game, babe?
Derek: Great! Chauncey Billups scored 35 points!
Sarah: Oh, that's awesome, hunny!
Derek: But no points were as big as this one. Open your fucking mouth you dirt-whore!
Sarah: Oh my! Why?
Derek: Because you are asking for a piston pump, you half-retarded hooker!
Sarah: Well, ok... (opens mouth and gets on knees)
Derek: How d'ya like theeat! (urinates in mouth) Hold it! Hooold it! Don't swallow! (proceeds to "Piston Pump" her mouth) Congratulations, you are now a "Detroit Piston (pissed in)"!