Cold Pee, or simply "coldpee" together, is the act of following a friend into a restroom facility and throwing a glass of cold water at them while they are peeing, yelling "cold pee!" at the same time. (Pee is warm/hot, hence the name, "cold" pee.) While this is typically done to men while they are peeing in urinals, there is no set rule. It is however, almost completely necessary to limit this prank to those you know - otherwise, a restroom rumble with a stranger is sure to ensue.
Man 1: "Hey guys, be right back, gonna go take a leak."
Man 2: (whispering to other friends as Man 1 walks away) "I'm gonna go COLDPEE him."
All friends: (quietly, but enthusiastically) "Yeaaaaah, DO IT!"
Man 2: leaves table with glass of cold water and runs off to the restroom
Man 1: (probably whistling or clearing his throat while peeing)
Man 2: sneaks into restroom and yells, "COLD PEE!" while splashing the glass of cold water all over Man 1
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