Onioning 

when a guy is dancing behind an unknown girl , for example in a crowded disco or pub , and He is trying to put his pelvis as close,of the girl's bottom as, he can, following the rhythm of music while He is faking to dance.

Girl: She was onioning so hard on my ass last night! I thought it was gonna go numb!!

Onioning by SpanishUrbanBoy September 19, 2016

Onioning 

When you shoplift from the supermarket by scanning items through the self-service till as an onion (the lowest price item).

In a shameful display of self destruction, depression and sickening greed (potentially malice), pitiful celebrity TV 'chef' Anthony 'The Abhorrent' Worrell Thompson was caught literally red handed onioning a bottle of red wine and some camembert. His family are dutifully shocked.

Onioning by jamejame January 21, 2012

Onioning 

To make a promise to do something and then refuse out of a claim of complications or disagreement that never happens.

"He's not onioning his way out of the interview."

Onioning by NatrixMonster March 31, 2020

Devil's Onionring 

Your asshole.

Take a shower nozzle, turn it to jet, and give your devil's onionring a blast from the past!

Devil's Onionring by [sT]Crew March 23, 2004