P.U.: Perfectly Unacceptable
There are some whacky guesses, such as an early marketing campaign for deodorant that fights Personal Underarm odor.
But this much is certain: the Indo-European root “pu-” means “rot” and “decay”, words obviously associated with objectionable odors. Think putrid, pungent, or even puke.
Another possibility is that P.U. is short for putro, puter, puteo, Latin words for putrid, foul, stink, be redolent, or smell bad.
Any way you slice it, this is an interesting factoid to bring up at your next boring holiday party. And make sure you tell folks you read it on the Trafon blog first!