"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!