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

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

Underfag 

Any Undertale Player/Fanboy that meets the following Criteria.

1) Is obsessed and will go to any length to get the merchandise .
2) Is under the age of 10.

Guy A: God Damnit
Guy B: What?
Guy A: My little brother is such an Underfag

Underfag by ExtraShard July 4, 2016

Underfag 

A person who is a huge fan of the indie game Undertale or Deltarune.

Dude 1: "Why does your friend always go on DeviantArt for Undertale fan art?"

Dude 2: "Oh, he's an Underfag. He raves about it like it's the best game in the world."

Underfag by That2000'sKid August 3, 2019

Underage Drinking 

1. Something that is punishable only in the U.S.

2. Something that 18, 19, and 20 year olds can be charged with in the U.S. due to their fascist drinking laws.

3. Something they don't allow 18, 19, and 20 year old American soldiers to do before they come home from Iraq in pieces with only an American flag handed to their family for comfort.

(in the U.S.) You are a month away from your 21st birthday and are drinking a beer! Thats underage drinking!

(everywhere else) Hahahaha look at that stupid drunk 15 year old!

Underage Drinking by MacDAS January 12, 2007

undersage 

Lacking maturity or wisdom.

He may not be underage, but he's sure undersage.

undersage by ZarahiL September 15, 2018

People Against Underage Driving In Reverse

People Against Underage Driving in Reverse, or P.A.U.D.I.R. for short, was formed on January 10th, 2007 after an accident in a residential driveway caused thousands of dollars in damage to a vehicle. The driver not named and under the legal driving age, put a truck in reverse and crashed.

The main mission of the P.A.U.D.I.R is to fight to keep residential streets, highways, and driveways safe from underage driving in reverse....

Oh Shit, People Against Underage Driving In Reverse are going to hunt that bitch down.

People Against Underage Driving In Reverse by Steve Perry January 12, 2007