when a guy is boning a female and he feels like he is just about to bust a nut, so he pulls out of the chick but doesnt bust, so he can continue to keep boning. a false alarm. it happens every once in a while.
Guy:oh this feels good, im about to bust.
Guy:nevermind. false alarm
Girl:did u have a premature pullout
the act of two women scissor together, usually lesbians, and one females shits into the other females vagina. The "taco" is referring to the vagina.
girl 1: Hey, you want to go have a shitty taco
girl 2: Sure, i would love to!