Abreviation for United States of Merica. This is the phrase for a stereotypical 'American' that sees themselves better than everyone else. This term is most commonly seen used in a sarcastic tone and southern drawl to appear as egocentric and to make light of a situation in a joking manner.
"This is the USM."

"The what?"

"The United States of Merica. Speak English or go back to China."

"I'm not Chinese I'm Korean."

*Confused look on face* "WTF is that?"
by etilauqa March 08, 2010
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Underground Sex Machine.
A female, usually with lots of black eyeliner and a mohawk, who enjoys getting fucked hard.
"I am a USM."
"Drop ya pants."
"Fo' shizzle."
by Afro Man October 31, 2003
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Stands for "Unbelievably Slothful Man"...A general term given to a person, usually your bosses, who continually pass their own work-load onto others in their employ...Commonly believed that such a fucktard will leave work and go home to lazy land to become a Bag Whacker again...
USM: "eeermmm....Karim, can you just do this for me..."
Karim (Depressed Employee): "mmmm...yeah, when I have time"
USM: (Leaves room)
Karim: "Fucking USM"
by Macster007 November 30, 2006
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By the one the only, the succesful failer ,the winning loser, the acceptable reject, Afroman the best rapper in the world to date on the song "Back to School" and if any of yall have sumthin to say about it you can go suck on ludacris's ass because he sucks and he only talks he doesn't even rap to the beat
Afroman: "Mama, ima go to the Univeristy of Smoking Marajuana all of my friends go to USM so ima tag along and hit tha bong wit them..."
by Hairy Culo February 23, 2005
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1) Acronym: Unstoppable Sex Machine. Once used by the long disbanded British act, Carter USM.

2) Ultra Sexy Matsereguru. Alias of Dung Beetle, a once active member in the South Park online community who has vanished into obscurity.
by anon August 21, 2003
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1) Whats USMS, its like a pile of dog crap, no one knows where it came from or how it got there but when you see it, all you know is its a load of shit

2) United States Mystery Service, or, United States Made-up Service
"LCDR Reagan, wait, wasn't he a gunnery sergeant in the marines?" "Yea, but he joined USMS and anything's possible there"
by Captain _____ GC September 14, 2013
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Abbreviation for "Unstoppable sex machine", as in "Carter: The unstoppable sex machine"
by Kung-Fu Jesus May 16, 2004
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