NFL Star Chris Johnson -- Threatens Lawsuit Over 'Dreads on a Stick'

Tennessee Titans running back Chris Johnson ain't just takin' on the Bengals this weekend -- he's also going after two guys allegedly trying to profit off the NFL star's dreadlocks without his permission.

Johnson is furious ... after learning about a product called, "Dreads on a Stick" -- which were being marketed as fun wig-type thing fans can wear to support CJ.

The guys behind the product launched a website to sell the "Dreads"-- which featured Chris' name and image.

But CJ tells TMZ ... he NEVER approved the product and doesn't want his fans to be duped into thinking he had anything to do with it ... so he's unleashed his lawyers to make things right.

Johnson tells us, "My lawyers on are on it ... the site has already been shut down ... and I'm investigating to see if these guys made any money off of this deceptive scheme."

TMZ spoke to one of the guys behind "Dreads," who tell us, "This is bulls**t ... we're going to put this site back up and still promote dreads on a stick."