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2.
A psychotic young man with no life and a strong interest in killing people with a cardboard sword. If the world were to end tomorrow, Underwood would rather play video games while sitting on top of the dead, rotten corpse of his roommate that is still decomposing in the other room... Right now. <.< >.>

Ahhhh... What a wonderful world.
OH SHIT! IT'S UNDERWOOD! RUN FOR YOUR FUCKING LIVES!!!
by I am Underwood. Fear me. May 20, 2009
 
1.
A desire or urge for retaliation. To get even with somebody, payback time.
Don't make me go underwood on you.
by Rider Joe May 09, 2009
 
3.
What happens when a male has an erection while their penis is pointing downward. Can also be used when one has a visible erection while under a blanket.
"Does Greg have a small penis, his boner looks really small"

"No, that's just underwood".
by Ninakula May 15, 2010
 
4.
Derived from misunderstood, it is when no one you in your groups of friends understand the thing that turns you on or makes you happy.
Thomas is misunderwood by his friends for his love of fantasy football.
by Me, myself, and I. November 20, 2013
 
5.
looking like or having the appearance of a horse
Damn, that Taylor is such an underwood.
by BonerJamsSummer2003 December 05, 2009
 
6.
Erection,
Slang inspired by country singer/american idol winner Carrie Underwood
Did you see the hot, blond American Idol singer? That Carrie gives me underwood!
by Jack Schmack December 29, 2008