10:20 AM PT -- Tesla's stock plummeted as much as 10 percent and was down 6.9 percent at the time of this update, on the heels of Elon's smoke sesh and news that 2 senior execs are leaving the company.

The signs were always there, but now we know for sure Elon Musk likes to smoke ganja.

Elon got high as the clouds with Joe Rogan, blazing it up on camera Thursday as they talked about Tesla's plans for an airplane.

Joe sparks up a blunt -- marijuana rolled in tobacco -- and Elon takes a monster rip.

Pass the Dutchie!!!

There were always hints Elon was a fan of Mary J, and now we have our proof!

Dude launches rockets into space, sent a car to Mars blasting David Bowie's "Space Oddity" and thought about taking Tesla private at $420.

Nothing wrong with a little herbal medication, right?!?!