Under-carriage munching 

A term coined by a cool Aussie chick used to describe when koalas go downtown on each other.

‘Hey Davey, koalas are cute but most of them have Chlamydia. Probably from all their under-carriage munching.’
‘It sounds fucking sickening.’
‘It is fucking sickening Davey, it is.’

Under-carriage munching by milliesofmelbourne June 20, 2020

Under 21 Tax 

The difference between the amount of money given to an over 21 year old person by an under 21 year old person to buy alcohol and the actual cost of the alcohol, kept by the over 21 year old person as a payment for the service.

Under-age person: Hey, this bottle cost $17 and I gave you $20 - where's my change?
Over-age person: Sorry... Under 21 Tax.

Under 21 Tax by jonukas May 18, 2007

Under the Knife 

This phrase is often used to describe a surgery or sugerical process. Knife standing for “surgery” was first recorded in 1880.
Example:

Sam: "When do you go under the knife?

Tim: "I have surgery next Wednesday. I have to take an

Ativan before I get there."

Under the Knife by SigmaNutz December 27, 2011

Under-dramatic 

The opposite to Over-dramatic.

Someone who is under-dramatic is not easily surprised/impressed. They don't exaggerate or get excited.

"Kyle is so under-dramatic, i told her i was pregnant and she was just like 'cool talk to you later', "

"Yeah she is totally under-dramatic Sherly - congratulations btw - when were you going to tell me?!"

Under-dramatic by BrainMaster June 3, 2014

Under the stars

Under the stars meaning wanting to have passionate sex under the night sky, preferably with a picnic

Omar says to Larry that he wants to rail Nancy under the stars. Larry says me too.

Under the stars by Yeet master124578 February 1, 2021

Under levered 

A malaprop for under leveraged, used only by society's most egregiously underqualified businessmen or presidents.

"I'm totally under levered" - said the commander in chief.

Under levered by freighttrain1976 October 15, 2020

under sextimate 

The act of under estimating one's sexually ability.

That girl's fuglyness led me to assume she would be bad in bed. Oh but did I under sextimate her, that was the best night of my life.

under sextimate by Dericious08 July 8, 2014