Cooking onions 

When someone has a bad body odor.
When someone’s armpits smell like onions.

Guy 1 : “Bro do you smell that?”
Guy 2 : “Yeah, I think sam is cooking onions”

Cooking onions by Tangy bbq sauce March 13, 2020

cookin' onions in the oven 

The act of stuffing a girls vagina full of onions, and then proceeding to eat her out until all the onions are gone.

Luke: Hey man, have you seen the onions around?

Tyler: Ya, sorry! I was cookin' onions in the oven with my gf last night!

cookin' onions in the oven by Not Mike M November 15, 2013