This is a phrase for when you're extremely pissed off. You're so pissed off, you start pissing out skittles. Possibly even the ones you bought at the movie theater for $17.
I was dancing with this girl at the club until Justin Bieber cut in, I was pissing skittles.
Kim Kardashian told me that she was pregnant with another man's baby, I was straight (str8) pissing skittles.
Megan Fox told me she has herpes, I'm pissing skittles, literally.