The act of a female grabbing a guy's sex organ to check it for suitability before committing to further sexual acts. Not quite a handjob, but a possible precursor.
Kat wanted to go further with Steve, but when she got her hand down his pants for the oncey, she knew it had to end there.
by texasshole January 30, 2011
1 more definition
derived from "once over." The act giving a hand job, but not really.
Dude I totally got a oncey from that chick. She was so drunk she couldn't finish.
by onceylover February 16, 2011