Originating from the badass song by Tech N9NE, T9X (referring to Tech N9NE Experience / Ecstasy), also alludes to experiencing 9 drugs at once.
Tech N9NE mentions Ecstasy ("Motorola"), Caribou, GHB, Shrooms, Marijuana, Acid, PCP, Codeine, and Robitussin, adding up to the most bad ass song ever.
Person 1: I'm T9X'n tonight you down?!
Person 2: Yeah dude lets get fucked!!