50 Cent's smartphone just got banned from bankruptcy court ... because the judge thinks he's using it to make a mockery of the case.
The judge banned all electronic devices from the courtroom and conference rooms in response to Fiddy's last court appearance. You'll recall he posted a shot of himself last month with a wad of possibly fake cash in his waistband ... while a hearing was STILL IN PROGRESS.
The judge said she's all for free speech, but implored 50 to quit with the antics and take the case seriously.
The only good news -- the judge gave Fif props for moving in a good direction, financially.