Mally Mall Slays Birthday With $900 Joint

"Love & Hip-Hop: Hollywood" star Mally Mall got a stoner's dream gift for his 38th birthday ... a 4-foot blunt disguised as a weed sword, and he smoked it all at his Ace of Diamonds birthday bash while shooting out $50k from a laser gun.

The mega-joint was a gift from B-Real of Cypress Hill. The two are actually partners in the weed biz and their hallmark is packaging joints in creative silhouettes.

We're told B-Real rolled about 3 oz of weed into Mally's present ... totally legal in California where anyone with a medical license can possess up to 8 oz. As for the price ... $900 since it was packed with M&M Cookies -- not the candy, but the award-winning weed strain.

As it turns out ... it still wasn't enough to go around, so they sparked another blunt, this one shaped like an uzi.