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TISG= an acronym for "That is so Gay." An expression used to describe unusual, undesirable, or uncomfortable situations. Often looked down upon for its homophobia association.
Person A: I went trick-or-treating last night with Tyler!! He went as the tooth fairy!

Person B: Isn't he, like, 50 years old??????

Person A: Yep.

Person B: Omg, TISG!
by Mimzily Madness July 13, 2010