Anything that evokes a strong feeling of disgust or repulsion and/or a person who perpetually ruins good times. Butt Onions can also be used to describe your strong feelings as to what is "uncool" or just plain awful and unpleasant.
"Don't go in there, Joe just ripped a butt onion"

Allen : "Wanna ding dong and ditch?"
Burt : "Nah man we'll get caught"
Chris: "Burt, don't be such a butt onion."

"That movie was terrible!" "Yeah, totally butt onions."
by NzappaZap June 12, 2013
Get the Butt Onion mug.
an ass so beautiful, it makes you cry.
(ass sliced onions do)
An ass that is so mesmerizing to look at that it gives you an instantaneous chubby.
Check out the onion butt on that slut!
by weave April 3, 2003
Get the ONION BUTT mug.
An Onion-Butt is ther perfect ass on a woman or man. The word Onion-Butt has said to make the grown man cry because it is so beautiful.
Damn, that girl got an Onion-Butt!!!
by Steve Y October 18, 2005
Get the Onion-Butt mug.
So beautiful it makes a nigga wanna cry.
"wow, thats an onion ass, im tearin up baby"
by nitey March 30, 2005
Get the onion butt mug.
Someone who has an ass so fine it makes you want to cry.
"I like girls with big tits and an onion butt!"
by angeleyes228 January 8, 2012
Get the onion butt mug.
A booty that makes one's eyes water
Yo, that girl got an onion butt.
by Jakethesnake July 13, 2006
Get the onion butt mug.
A butt that brings tears to your eyes.
I like a girl with fake tits and an onion butt!
by mg04mho August 5, 2011
Get the Onion Butt mug.