The natural response when an individual is asked if they have everything.

Somewhere at the start of Shrek 1, Donkey is being a dick and Shrek stars chatting shit about onions. He tells Donkey that "there is more to ogres than people think" and says that ogres are like onions, they have layers. This is called the 'Parable Of Onion'.

(DISCLAIMER: DO NOT USE IN R.S EXAMS. YOU WILL NOT GET THE MARKS)

When you've wiped 10+ times and it's still leaving a trace.

A wet and creamy vagina that smells so rank it makes your eyes water.

the sound of balls banging ass.

A sexual act involving the insertion of a male's penis into an onion in an erotic manner

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.