It's when two chicks sneak off in one of their boyfriends' S.U.Vs for some girl on girl fun. It got its name from a chevy tahoe and the slang word for vagina, taco.
Guy: Hey where did you go last night??
Me: Oh I went to Tahoe Taco for dinner.
Guy: I've never heard of that restaurant before!
Me: Um, it's not a restaurant. Tia Jamison and I snuck off in her boyfriend's Tahoe for some "girl time". Boy was her taco yummy!!
Guy: Ohhh... Nice. Next time you go to eat out, lemmie know so I can join!
Me: Nope, sorry. No burritos allowed!!