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1.
p3ni5 means penis!

it is created by fact that character 'E' looks similar to number 3 when flipped around and character 'S' looks like number 5!

if someone wants to write word 'penis' but doesn't want to swear (penis is not a bad word, although some people might think it is) or wants to deliver word differently, he/she will write it as 'p3ni5'!
chat:
Person1: have you seen that video where guy shows his p3ni5 on camera?
Person2: No i haven't!
by Electron energy February 07, 2014