When something is on or when something is so on. When something is going to happen or happen intensely it becomes option to add the zo. It's commonly used when a guy thinks he going to score with a girl. Also used when a guy is about to fight another guy.
by Chris Callan January 12, 2009

Good-looking; attractive; hot
by Pirate Gurrl January 23, 2017

Some sweaty bastard that plays Fortnite all day and that’s very short. Also thinks he is the best keyboard and mouse player in the fucking world
by IfYou’reReadingThisUrASweat December 09, 2019

She wouldn't swallow so he blew his load on her chest. Did he at least onzo it?
The dude thinks he's a super hero in bed. Every time he has sex he throws down an onzo.
She freaked out about me blowing my load in her, so I just onzo'd her.
The dude thinks he's a super hero in bed. Every time he has sex he throws down an onzo.
She freaked out about me blowing my load in her, so I just onzo'd her.
by Stenk December 28, 2008

by pɐp ɹn November 22, 2021
