Top Definition
When you burst out laughing, so hard and so suddenly, you involuntarily fold in half at the waist. Usually accomponied by a large exhale of breath.
It was hilarious, and when he hit the punch line, I jacknifed.
by KeriBlog March 20, 2012

The Urban Dictionary Mug

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The Urban Dictionary Mug

Lotsa space for your liquids.

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The Urban Dictionary Mug

Your favorite word on a white mug.

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The Urban Dictionary Mug

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).

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Photos & Videos
a bad ass close to the same qualities of Jesse James and D.B. Cooper. Also has an extremely huge dick and is amazing in bed.
damn, that guy nicknamed jacknife kicks my ass!

yeah i know, he banged my girlfriend then dumped me cause apparently he fucks her better.
by slappy bags February 04, 2010

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Your favorite word on a white mug.

Create a mug

The Urban Dictionary Mug

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

Buy the mug

The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

Buy the t-shirt

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