Top definition
A big peice of shit, also known as "Mike", or "uni", or "Koala Bear". All mean the same thing. An asshole.
Your as dumb as a koser!
by DeadzeroCustom August 18, 2003
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2
When you go to the bathroom to take a shit and instead of it being enjoyable. it feels like the world is ending if only the smell dosent take you first.

It may often splash up, as a final "fuck you" which makes the wiping process that much worse.
X:Dude I dont know what i ate last night but I just dropped a koser and am still surprised im here.

Y: Yeah man, those really can ruin not only a day but a week.
by Gern-haha December 13, 2010
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3
for something to be nasty, not right or just something you wouldnt do
oh my goodness did you see her nappy hair, i swear that aint koser
by chanae November 22, 2003
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