COLD: Young Jeezy Fires Back at Alleged BFF ... I Don't Owe You $5 Mil!!!

Young Jeezy is a rapper ... so when some guy in Georgia sued him for MILLIONS -- claiming he's entitled to half Jeezy's budding empire -- the rapper had four words ... WHAT YOU TALKIN' BOUT????

Jeezy was sued last year for $5 million by a man named Ellerbee Demetrius, who claimed he helped make Jeezy's career and is now owed money from at least 4 of his albums, including "The Inspiration" and "The Recession" ... both of which went platinum.

Ellerbee claims he has been best buds with Jeezy since 1995 and after meeting him at boot camp, the two formed a couple of record companies together, released a few mix-tapes, and spent their time nurturing Jeezy's career.

Not only that, Ellerbee says when Jeezy hit the big time with Def Jam, he executive produced those studio albums.

The problem ... Jeezy says Ellerbee is FULL OF S**T.

In fact, in recently filed legal docs ... Jeezy denies being Ellerbee's best friend (sad), denies forming ANY music companies with him -- and says he 100% NEVER entered into any agreements (written or oral) to share HALF his profits.

The case is still pending.