A 'third fuck' is an unwanted person who enters an argument that is already ongoing between two people
Person 1: fuck you!
Person 2: no, fuck you!
Person 3: fuck both of you!

Person 1&2: shut up you third fuck your not involved in this!
by Derek858564 July 4, 2018
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Someone who teams up with imposters in the game Among Us even though they are a crewmate.
Blue (Crewmate): Pink is clear, I was with him the whole time. Has to be orange.
Pink (Imposter): Yeah, Orange is imposter.
(Blue is third impostering)
by kamakiwi November 1, 2020
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A third imposter is a person who acts like an imposter in the game among us while he is an innocent crewmate and gets every other innocents killed
Oh look a confirmed crewmate who scanned
D4 being third imposter: omg that person is an imposter I saw him vent I swear

*Innocent confirmed crewmate gets thrown out the ship*
by The Funny Guy 69 December 23, 2020
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Ninja is the third imposter.

Example: "It's Pokimane, and Valkyrae! 1 Million Percent!!" (Not Them) "Thanks for being the third imposter Ninja!"
by LAMOW October 23, 2020
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When you are getting oral sex and you grab her head and miss giving her a hole in her neck
i was getting head and i pulled out to try to ram it down her throat i missed and poke a hole in her neck giving her the third arm clothsline
by ralphieakabigd December 2, 2007
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