What a female does the following morning after indulging in unprotected anal sex with a gay man who, typically, is highly desirable to both men and women, making the term one of begrudging admiration.
Lexi "Did you see Candy last night, she's such a sexy slut; she even trapped Todd?" Eva, "you mean Todd, the gay barman with the body to die for? Wow, I guess she"ll be shitting rainbows and unicorns this morning; bitch".
Girls who wear ridiculous amounts of colours on their clothing. Play safe. Play black.
"Brittany didn't get the memo about always wearing black, it's 2016... She looks like a rainbow took a shit on her
"Yea totally a rainbow shit."
A stool with substantial length and exit velocity, causing one to ponder butt sex while finishing their time on the toilet.
He: "Man that rainbow shit made me look at Steven differently."
Her: "Ugh why are guys so gay"
An unbelievable occurrence, similar to oh shit or oh snap.
You got to be Rainbow shitting me?!?