It is derived from the word "jizz," which is its male counterpart and equivalent--even though the two are completely different fluids. Here is a little equation:
his = jizz hers = jerzz
v. to ejaculate on someone's (either male or female depending on a woman's sexual orientation) face. The female equivalent of ejaculating.
also, see jerzzed, jerzzing
Guy 2: Tight, what happened?
Guy 1: Man, everything was going good. We were fooling around, I ate her out, and then she came...
Guy 2: Nice!
Guy 1: Nah, dude, she jerzzed in my face!
Guy 2: Ah, that sucks.
Guy 1: The jerzz soaked all the way through my mattress!
Guy 2: Bummer.