Derived from snitch, a universally hated type of person.
Person A: Sup man?
Person B: Not so good, this week's been really Snitchy.
Person A: How so?
Person B: My girlfreind been acting like a bitch lately. and on top of that, my computer's hard drive got corrupted.
Person A: Aww, that's fucking Snitchy dude!
Person B: Really Snitchy!
Person A: Hey, wanna go get some McD's?
Person B: Nah, that place is snitchy. It gives me bad vibes.