verb, to forcibly insert an object (usually a knife) into a person or animal's face.
noun, used to describe a situation, often unfavorably
verb, "If you don't shut up about your sister's operation and take off your pants, I'll facestab you!"
noun, "Your parents died in a car accident AND you lost your wallet? That's a facestab."
When a french douchebag kills you instantly by swinging a small knife in your face.
"WTF? WTF? WTF? THAT AFRICAN SPY BULLSHIT JUST FACESTABBED ME"