Undergasm 

When you understand something and turns you on to the max and you cum

Dude I get it now, I think I had an undergasm

Undergasm by Ahshdbfhd November 24, 2020

Undergasm 

When you finally understand something and have an overwhelming happiness, you cum

Dude I get it now, I think I had an undergasm

Undergasm by Ahshdbfhd November 24, 2020

tucked like underarmor 

To conceal carry a firearm at all times.

Friend: bro, I’m nervous what happens if somebody tries to rob us?

Friend: don’t worry, I got that heater tucked like underarmor.

tucked like underarmor by AlwaysTucked July 31, 2021

undersmile 

Euphemism for vagina. Coined by Joy in the TV comedy "My Name Is Earl".

Joy: "We gotta work backwards. Like when you rewound that videotape to see if Sharon Stone really flashed her undersmile."

With "flashed her undersmile", Joy is referring to the film Basic Instinct, specifically the scene where Catherine Tramell (Sharon Stone) distracts her interrogators by uncrossing her legs to reveal a lack of underwear.

undersmile by dee kay April 14, 2008

raving underpass

The act of dancing underneath a concrete structure, to any given beat. Usual participants are gothic warriors and princesses.

Buddy and Joe were raving underpass I-95 over the weekend.

raving underpass by WebstersBest June 8, 2016

Tucked Like Underarmor 

To conceal a firearm in ones waistband so snug that it resembles the tight fit of Underarmor.

Dylan: Hey man I'm kinda nervous we might get robbed...
Doug: Don't sweat it bro, I got that thang tucked like Underarmor.

Tucked Like Underarmor by AlwaysTucked August 25, 2021

underpaste

The uncomfortable feeling when the skin of the male genitalia is stuck together in the underwear.

A girl in my class saw me as I tried to fix my underpaste.

underpaste by LoLo1234 August 1, 2008