A term used to describe a woman involved in a healthy romantic relationship with another woman. Can be used plurally to describe two women involved in a lesbian relationship as well.
"Don't even think about talkin' to Jennifer. Bridgette is her soultaco."
A vagina, or taco, that is toxic. Usually ridden with multiple STDs, it's very gross, and is similar to muff cabbage. Also anything from Taco Bell, or Taco Bueno.
Guy 1: Hey mate, who's that girl over there? She's pretty cute.
Guy 2: I wouldn't touch that if I was you, apparently she's got a mouldy taco.
Guy 1: Shit man, cheers for the advice!