What does 1, 3, 5 rule mean? July 19, 2017 All Dictionary 1, 3, 5 rule meaning in Urban Dictionary when utilizing public bathroom, making use of urinals, 1, 3 and 5. No 2 and 4 just in case other individuals can be found in. Not be close to another guy making use of a urinal. Also no chatting the reason why with the bathroom.