The act of anal sex when the man urinates into the girl or guys ass, filling the anal cavity with piss. Then remove the penis and smack both ass cheeks together causing the urine to squirt into the air like a water fountain. Then you may drink or not drink.
Guy 1: "dude i was so thirsty when i was banging my old lady in the ass last night"
Guy 2 : "what did you do?"
Guy 1: "I did the old Turkish Waterfountain"
Guy 2: "Thats just sick man"