Third Imposter

Someone who is unknowingly tricked into actively working against their side and themselves. The word comes from the game Among Us which is a murder mystery game where there are 2 murderers called imposters.

Yellow: I was in O2
Blue: No you weren’t, I saw you vent in electrical.
Green: yellows clear, if he were imposter he’d have killed me many times. Blue I think you’re the imposter.
Blue: Stfu green. You realize you’re the third imposter, right?