Chris Brown -- My Lambo Just Got a NIKE PAINT JOB

Chris Brown just did it ... he painted his Lamborghini Aventador just like a Nike Air Foamposite Camo sneaker ... just for the hell of it.

We spoke to the owner of JC Customz in Bellflower, CA -- who tells us Chris rolled into the shop last month -- along with the Nike shoe -- and asked the guys if they could replicate the camo pattern on the car.

We're told the work took 4 weeks to complete -- all handpainted, no wrap -- with the total cost running close to $15k.

But it was obvious Chris felt he got his money's worth -- 'cause right after the job was complete, Chris posed for pics with his freshly painted toy.

Chris also grabbed a spray can and tagged some of his signature monster characters on the walls inside the shop -- and the owner tells TMZ he's stoked about the new art.

It ain't the first time Chris has applied an unusual custom paint job to a super expensive ride -- ya gotta check out the gallery.