Underfug 

British slang for ones undergarments

You just shat your underfug!

Superman wears his underfug on the outside.

Underfug by a.non.ee.mouse August 5, 2009

underbugger 

A person or annoyance that gets under ones skin and bugs them.

That squeaky door is a real underbugger. I think that new girl is an underbugger, she wont shut up.

underbugger by Christopher Evans August 2, 2008

Underfucked 

sexually deprived

1. Yo look how hard she's hitting on him... she's definitely underfucked!

2. That guy is completely underfucked. He just desperately asked her out again after she told him to fuck off for the third time...

Underfucked by Stephen and friends June 26, 2010

underfuckingstand 

When you don't understand something and you are super pissed.
When you don't feel like saying "fucking understand"
When fucking understand just doesn't quite display the needed emotion.

"I don't underfuckingstand why your acting like this"

underfuckingstand by Desiree Aho January 9, 2008

underfag 

People in the Undertale fandom. They tend to be made fun of for being butthurt and cringe-worthy. Among other things, they are also annoying.

Hunter: Undertale sucks.

Underfag: Hey!! Undertale is good the fandom just sucks but Undertale is good and has good ships lol XDD!! Everyone has their own opinion!
Hunter: Then let me share mine.

Underfag: You're just being stupid let me have my own opinion!

Preston: They took the bait.

underfag by IgnitingInsanity May 26, 2016

underfuckingstand 

underfuckingstand - Understand, with "Fucking" inserted in the middle, making it an exclamation of frustration or, in some cases, a joking statement.

"What part of this do you not underfuckingstand?!?" or "I dont underfuckingstand!"

underfuckingstand by Steve October 24, 2004

underfag 

Someone who is waay to obsessed with Undertale. They often say "I'm filled with determination" or make skeleton jokes. Like the character, sans does. They also bring up Undertale way too much.

Friend 1: Wow dude, that episode truly was sans-sational!
Friend 2: Stop being such an underfag.

underfag by DerpRunner October 7, 2016