Nick Diaz Smokin' with Snoop

Nick Diaz's smokin' tour continues ... this time, he stopped by Snoop Dogg's studio and burned with the rapper -- and it was all on video.

The UFC superstar -- and avid pot enthusiast -- was a guest on Snoop's GGN Network show ... where the two appeared to smoke some weed and hang out.

Just last week, Diaz lit up with Tommy Chong ... and before that, he kicked it with Snoop backstage at one of the rapper's shows.

Long story short ... Diaz is proud of his marijuana hobby and clearly doesn't care who knows it.