Acronym that stands for "Weekend Of No Inhibitions". WONI is a state-of-mind one must undertake during extremely fun "friend only" weekends (Note: If significant others are involved then achieving the appropriate state-of-mind is virtually impossible). Pronounced as follows - wah-nee.
"WONI" can also be used to describe an extremely entertaining all-weekend event or a person's particularly fun behavior at said event.
ENTERTAINING ALL-WEEKEND EVENT
Guy 1: This bachelor party is gonna be awesome. We are gonna drink a ridiculous amount of booze, dominate the Blackjack tables and make it rain at the titters.
Guy 2: No doubt. This weekend is gonna be WONI.
PERSON'S BEHAVIOR AT EVENT
Guy 1: Did you see Tommy take three shots of tequila and then make out with some random girl, all while getting a lap dance from some Russian stripper?
Guy 2: Yeah, that was so WONI.