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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
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2
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
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