Even adults believe this myth thanks to movies like “Grown Ups” where Kevin James’ character pees in a water park pool, turning it blue. The truth is a urine-revealing pool chemical does exist, but isn’t actually used. If it was, every public pool you visited would be disgustingly turned blue. My own sister peed on me at a water park and there was no evidence besides her evil laughter. I can forgive, but I’ll never forget Sarah.