Kevin Pedersen, 20, who calls himself King Kevi, made a mini-name for himself by pretending Bieber's best friend, even claiming to live at the pop star's Calabasas home for free.
But as it turns out, Bieber was none too pleased at Pedersen's attempt to filch off his fame, especially after the interloper staged photos that tried to make it look like he was getting cozy with Bieber's ex, Selena Gomez. In fact, a source close to Bieber said the pop star has never even met Pedersen.
Now Pedersen has filed a request for a restraining order, claiming the star sicced his legions of fans on him in revenge.
The request says Bieber tweeted out Pedersen's cell phone number, then deleted it a few minutes later. Pedersen claims he's received "thousands of death threats" from Beliebers, and genuinely fears for his life.
Bieber's people say the singer never tweeted the number in the first place.