Top Definition
Flirting with or hitting on your good friend's very serious girlfriend. Named after "Koon" of youtube fame. Kooning is often made possible when the boyfriend is away and the girlfriend shows pity for the kooning boy which is misinterpretted by the desperate despicable kooner as affection. Kooning is not cheating because the girlfriend is very pleased with her current boyfriend which just makes kooning all the more despicable.
"Did you see Alex kooning last night? If Nick knew he would beat the shit out of him!"

"How can you respect anyone who koons as much as he does? Doesn't he realize he doesn't have a chance?"
by Bob321 March 17, 2007

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inserting objects into your peehole.
Dude, Daniel's been kooning with a torque wrench. His peehole's gotta be super ragged out by now.
by Bahn burner August 25, 2010

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One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

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The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

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The Urban Dictionary T-Shirt

Smooth, soft, slim fit American Apparel shirt. Custom printed. 100% fine jersey cotton, except for heather grey (90% cotton).

Buy the t-shirt