To convey the ultimate form of rage, despite how small the situation may be. Completely uncalled for, no matter what.
May also be used to describe any situation you deem fit.
Suzy and Rick were eating cookies. Suzy accidently dropped her cookie on the floor.
Rick said, "I'LL FUCKING KILL YOU. THERE'S NO FUCKING WAY THAT JUST HAPPENED. WHY THE FUCK DID YOU DO THAT YOU PIECE OF SHIT. I FUCKING HATE YOU. YOU ARE THE REASON WHY JESUS DIED."
Suzy cried herself to sleep that night because of Rick lethardusing her.