An action akin to the high-five or the handshake. The act of touching fists knukle-to-knuckle in greeting or departure. In 2003 this action was accompanied by the phrase "knuckle-up" but has since just become the motion without the phrase. The first instance of this action and phrase was in Dallas, TX in the mid-90's and has since become a common gesture in most public forms of transit in NYC.
Jimbo-- "Is that some kind of a gang sign?"
Miguel--"Nah, that's a knuckle-up, bro."
by super steve August 31, 2005
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To get belligerently drunk, to the point of blacking out and making choices you may regret
Anyone want to go get knuckled up at Applebee’s with me?
by TroopRespecter8 July 31, 2020
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Guy 1: Did you see Stacey?

Guy 2: Yeah, total nipple slip! I'm totally going to knuckle up to that later
by leobaby1 November 18, 2011
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When two men choose to engage in mutual masturbation, implementing a "thumb war" grip and jerking themselves off simultaneously, locked at the knuckles.
Since he had a girlfriend, the young man decided to knuckle up with a buddy.
by DaXymbiont February 7, 2018
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