A combination of the terms "poon" and "tsunami" referring to a tidal wave of girls, especially referring to ex-girlfriends attempting to have sex with you again. Specifically, this terms refers to an abnormally large number of girls trying to get with you in a short period of time.
Look dude, I can't meet you for drinks later. I am swept up in a poonami and I can'tlet it go to waste.