Patrick Schwarzenegger -- Miley's Fans Threaten: We Will Kill You

Miley Cyrus may be pissed off at Patrick Schwarzenegger ... but she's gotta do something to shield him from the death threats he's receiving from her rabid fans.

Patrick's assurances he'd never cheat on his lady have fallen on deaf ears, because Miley's legions are sending thousands of hate tweets threatening to kill him and burn down his pizza shop.

One fan warned, "you better run for your life when you come to LA" and "I hope your pizza place burns down." Another wondered, "Who's gonna kill Patrick for us?"

Others threatened all-out war "... be ready for what's about to come," punctuating the threat with a knife and poo emojis.

Of course, he couldn't escape without an Arnold reference ... "You and your dad have a way of f***ing good s*** up."

Yikes.