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1.
"You weren't at the party when it was invented". A word used when you have made a new word and nobody knows what that word was so you just say/write "YWATPWIWI".

what-pwee-wee (for those having trouble pronouncing it, silent Y)
Valerie: Hi John, you were so funny the other night I was Pmslsmicb

John: What the fuck are you talking about woman?

Valerie: Pissing myself laughing so much I couldn't breath, YWATPWIWI!!

John: Get out of my bed!
by Southwest Memes June 30, 2013