Snoop Dogg -- I Won't Drop a Dime On Justin Bieber ... Now Watch Me Pimp This Playmate!

You must have a mental disease if you think Snoop Dogg is gonna snitch on his buddy Justin Bieber ... 'cause he's too busy PIMPIN' PLAYBOY PLAYMATES ... and TMZ has the footage.

Snoop was bouncing from Supperclub in Hollywood last night when we asked about his naked beer pong game at J.B.'s super-secret Great Gatsby party last weekend ... but Lion/Zilla told us his lips are sealed. Gotta respect that.

Also gotta respect the fine ass Playmate -- Nikki Leigh, Miss May 2012 -- who went straight for the rapper like a heat seeking missile ... and let's put it this way, Snoop wasn't exactly shutting her down.