Check out the clip from February 2011 ... Diddy was sporting dark shades and sitting side by side with the much younger Biebs, with host Jimmy Kimmel parked behind his desk, chatting with the famous duo.

The convo started off with Jimmy asking Diddy and Justin what their relationship was about and if they were collaborating on music.

Diddy responded they had become friends "in a strange way" and Justin was like his "little brother," unafraid to call and ask him for advice.

The music mogul also explained the record industry was a strong family and Justin was someone they had their arms around to protect him from vultures in the music biz.

Diddy described Justin as "genuinely a nice person" with lots of talent, adding that "he's one of the greatest kids you could ever know."

Bieber smiled and shook Diddy's hand, telling Jimmy that the Bad Boy Records CEO had bought him a Lamborghini ... but he hadn't received it yet.

Jimmy asked Diddy when Justin could expect the fancy car -- and that's when Diddy gave a stunning response that didn't age well.

Diddy said, "[Justin] had the Lambo for a day or two and he had access to the house, and he knows better than to be talking about the things that he does with Big Brother Puff on national television."

As everyone in the world knows, Diddy was arrested by the feds for racketeering, sex trafficking and other serious crimes stemming from his notorious house parties involving drugs and prostitution.