U.B 

when you get a bonner when you dont need one.
Unnecessary Bonner.

i had a U.B this morning when i woke up.

U.B by mike.l July 9, 2006

U.B 

When you have an "Uncontrollable Boner" and need a hall pass to leave class early, commonly used as a nickname

Man 1: Hey, Whats your name?
Man 2: People call me U.B.
Man 1: Whys that?
Man 2: I CANT CONTROL MY COCK.

U.B by The Lindenhurst Crew April 3, 2008

u.b 

this means you got an uncontrolable boner!

damn man ive got a u.b

u.b by ice kidd March 31, 2008

U B 

U B, a shortened version of 'U B St00pid'. Only stupider. Was first used by Jesus in Roman Times when he was being trialed by Pilot.

Jesus - U B, Pilot.

U B by Vermillion Bagel January 13, 2009

U-B 

An exclamation yelled whilst making a u-turn in an unauthorized, highly dangerous area; often cutting off other motorists minding their own business.

"Holy Shit, you can't turn here...you're gonna wreck that asian kid on the tricycle...watch out... U-B!!!"

U-B by The T. isn't silent. May 6, 2009

u.b.i 

Unidentified Beer Injury

I woke up this morning with the weirdest U.B.I

u.b.i by d'minga November 3, 2003

U.B.T. 

Under Ball Tail

can be used to describe the excessive amount of hair growth in the gooch area. There must be long growth around the area (lower back and happy trail) to hint large growth of the gooch (hence the tail.)

Dude Nate, check that guy out! Talk about Teen Wolf, he's probably sporting a U.B.T.!

U.B.T. by RyPep May 19, 2010