Smith was walking around East Lansing, Michigan (the Cavs play the Pistons on Friday) when he started joking about how LeBron is following him everywhere.

"I can't go nowhere and get away from this motherf**ker," Smith said while pointing the camera at a Blaze Pizza sign.

FYI, James is an investor, franchisee and paid endorser of the pizza company.

Smith continued to joke ... "Look at this sh*t. Look at this n****. He everywhere. He just keep following me!"

Of course, Smith and James had the awkward moments when J.R. brain farted, and screwed the Cavs at the end of Game 1 of the NBA Finals last year ... but it's clear the two are still friends.

One more thing ... J.R. was spotted by some fans with cell phones and he DIDN'T steal them and throw them into a construction site!