The last thing 50 Cent needs is another lawsuit.

But that's what he just got, thanks to hit from his 2003 smash debut Get Rich or Die Tryin'.

Here's how it all went down.

In 2001, producer Brandon Parrott sent a bunch of tracks to Dr. Dre and Aftermath.

A couple years later, Aftermath admitted that Parrott's track 'BAMBA' was used in the 50 Cent featuring Snoop Dogg cut 'P.I.M.P.'

A signed settlement was reached, based on Dre and 50 teams's assurances that they didn't realize they were putting Parrott's track in 'P.I.M.P.'s' final edit.

Now, more than a decade later, Parrott says he has evidence that it wasn't an honest mistake. So he's suing both Dre and Fif for a bigger cut.

Even if he wins, he may have trouble getting money from 50 -- who's currently negotiating the terms of his bankruptcy with his creditors.

Dre, however, still has some of the deepest pockets in the entertainment industry.