verb: to "kill" someone - literally or figuratively
"if you ever bring up my ex's name around my current squeeze again.....so help me dude, I WILL flatline you!"

"I heard one of the perps got flatlined by the cops at that liquor store robbery last night."
by Hipster November 18, 2006
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brain dead, stupid , celebrally challenged, Stems from the flat line response of a dead person from ECG machine.
by Socrates September 15, 2003
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Someone severely lacking in personality; a person who kills any festive mood with their utter dullness
Dottie was having a good time, until she got stuck with that flatliner.
by D*Tice June 8, 2003
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Being so drunk that you blackout and can't recall a long period (an hour or more) from the previous evening.
I must have been flatlined last night, cause I don't remember stretching my scrotum skin in front of your parents.
by Chris Johnson February 20, 2004
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someone who is boring, unenergentic, tired, sleepy.
Dont be a flatliner! Here's a beer, c'mon lets get drunk!
by DanteM August 4, 2005
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1. To be dead, refering to how ECG machines' little green line goes flat when someone is dead.
2. To kill someone, literally or figuartively.
3. To be retarded, metally challenged, stupid, dimwit, and/or dumb.
4. A game where people choke themselves to get the feeling equivalent to be high. Therefore, legally high. Also known at the Choking Game and Space Monkey(s).
1. "Doc, the patient hass flatlined!"
2. a) The marine flatlined the Iraqi terrorist.
b) "I'll flatline you if you tell my mom I got a 46 on my math test!"
3. "Did you just figure out that water is wet? Wow Flatline, you're a few fries short of a Happy Meal.
4. A lot of kids accidently kill themselves trying to get high while playing Flatline
by Carrera's Wedge April 28, 2007
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A monotonous, expressionless person, lacking any enthusiasm or emotion. The term comes from hospital lingo, where a patient is said to flatline when a continuous straight line is displayed on their heart monitor, indicating death.
"...as excited as that flatline can get. I had to remind him twice to keep breathing."
by Der Golem February 7, 2010
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