G.T.I.S. Share definition Flag G.T.I.S is literal way of giggling, usually used over text. It stands for Giggling Titties. “OMFG I’m G.T.I.S.” G.T.I.S. by unicornglitterT0R4101 November 4, 2023 0 0 Get merch Get the G.T.I.S. mug. Buy Now — $32.95 See more merch