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Invertible

In linear algebra, an n-by-n square matrix A is called invertible (also nonsingular or nondegenerate) if there exists an n-by-n square matrix B such that:

AB = BA = I (where I is the Identity Matrix).

Otherwise, in life, it refers to the case where something can be transformed into something else and transformed back.
Randy: Sally is so invertible; real marriage material.

Sandy: I know, nonsingularly so. Put a few drinks in her and you can get her on her back and yet in the morning she still gets up and cooks you breakfast.
Invertible by Len Bakerloo July 6, 2016

Untetrible 

When someone is so good at Tetris they can't be beaten by the machine.
"Dude he is untetrible"
Untetrible by Mr Luva June 6, 2009

unvertisement 

An advertisement so incredibly annoying that it actually puts you off whatever it advertised.
I hate those unvertisements where they're having a clearance for furniture or carpets and someone is constantly shouting. They don't make me want to buy stuff, they make me want to find the manager of that place and shove a screwdriver down his ear canal.
unvertisement by Korgmeister April 22, 2006

Undertable Arnie

The Undertable Arnie

A sexual act wherein one partner bends over a chair and is stuffed under a table and acts as if they are "Arnie Grape" from "What's Eating Gilbert Grape", using such classic phrases as; "I could go at any time!" or "I kiled it. Gilbert!" or who could forget "Match in the gas tank, boom boom!".

These phrases are often augmented with mentally challenged sneering and shrieking noises mimicking that of "Arnie" from the movie.

The second sexual partner, of questionable intent, then begins to fornicate with the faux "Arnie". This sexual act is often ritualistically performed as a celebration for 18th birthdays in the midwestern communities of the United States.

Sometimes families throw a party and have cake afterwards.
Hey Pa, did ya hear? Muh sister gave me some good undertable arnie the other day! Ma taught her well!
Undertable Arnie by 500lbs_Mama April 11, 2026

sands undertable 

the sexiest (and laziest) skeleton there is

comes from the hit game undertable by robert fucks
i love sands undertable
More from Urban Dictionary

square grouper

Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.
"Base we've got some square groupers floating outside of Miami harbor."
square grouper by slipsheet November 6, 2004
Word of the Day on October 7, 2026
A girl who does ballet and only talks about ballet. Her schedule is filled with dance classes which does not allow her to do any other activity.
"Hey, do you know that girl Sally?"

"Yeah, she's kind of annoying. All she ever talks about it ballet."

"Wow, what a Bunhead."

"Hey Sally, you want to hang out this weekend?"
"I can't, I have dance."
"You're such a Bunhead."

"Yeah... I know."
Bunhead by Jen00 October 24, 2014
Word of the Day on October 6, 2026

trucker's tan 

A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.
I had a trucker's tan after driving for 10 straight hours on a sunny day.
Word of the Day on October 5, 2026
The phenomenon where adults salivate at children's toys
Every time I walk into the toy aisle, I catch myself kidulting over the latest action figures and LEGO sets!
kidulting by Emotional Cruiser October 12, 2025
Word of the Day on October 4, 2026
British slang for a scientist or technical expert, esp . when the speaker is not certain of the expert’s specific field of study. Not necessarily derogatory, but typically used by persons without a technical background. In the US, the equivalent would be “egghead”, “squint”, or “geek.”

Origin of the word is unknown. Started sometime in World War 2. Given the typical evolution of British slang, could easily have started because what these experts did was confusing or “baffling” to the common person.
According to the boffins downstairs, the murderer used a serrated blade.
Boffin by Agnon February 11, 2023
Word of the Day on October 3, 2026

Pee Calculus

When you have to pee in a movie but don’t want to miss anything, and must do the following mental equation: will the amount I have to pee cause enough discomfort to diminish my attention capacity for the remainder of the movie to an extent which is greater than the amount of the movie I would miss by making a mad dash to the restroom.
I saw Satantango last night, wonderful film but by the 5th hour I had to start doing pee calculus.
Pee Calculus by anorlondo October 1, 2026
Word of the Day on October 2, 2026
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