Understains

A name given by 1970s UK washing powder manufacturers for stains that won't wash out. A polite word for shit or bodily fluids of some sort on underwear.

"Has your washing got understains you can't remove"? "Use new Daz powder to remove them fast"!

by prof_evil May 14, 2011

Underbell

The underside of one's penis, usually towards the end.

Ouch my underbell!

by Tomujs August 7, 2012

Undercover Ginger

One who does not show visible signs of being a ginger (ie red hair or freckles), but days of not shaving reveal red facial hair. This allows the individual the ability to hide ones gingerness from the world.

By simply shaving his red beard, Tom was able to hide his true ginger identity and go about his day as an undercover ginger.

by Rgogo September 14, 2012

Underwater Pole Vaulting

verb. When a man takes a long and hard shit that pivots in the bottom of the toilet bowl then falls and hits the man's balls on the way down.

My balls smell like shit because I went underwater pole vaulting this afternoon at five past the hour.

by Scooter Harrington April 11, 2013

undefined behavior

Undefined behavior results when programs attempt to do things for which the standard defines no semantics, and requires no diagnostic either. Examples include dereferencing invalid pointers and dividing by zero. Executing such programs may cause them to produce incorrect results, crash, silently "work", or even format the hard drive.

It is commonly joked that undefined behavior allows the compiler to insert code that will start a game of nethack.

by henke37 May 23, 2014

undercock

A man who has smaller penis compare to his male friends'.

Tom: My gf thinks I have a big cock but she doesnt know that I am an undercock compare to what my friends are packing
A guy in the forum: Dude you sound so gay!
Tom: No I have seen them naked at the gym and besides I am only 5" long
A guy in the forum: lol you are an undercock indeed!

by jimissobored July 27, 2014

Undercover Chubber

When someone's display picture on a social media site makes them out to be skinny, where in actuality they are a massive chubber.

Hey bro, I just checked out her Facebook profile! Turns out she was an undercover chubber all along.

by MistoFisto March 21, 2015