Snoop Lion -- WEED JACKPOT ... Wins Pound of Weed Off Mayweather Fight

Snoop Lion was flyin' pretty damn high after Floyd Mayweather beat up Canelo Alvarez this weekend -- 'cause he won a POUND OF WEED in a bet he made on the fight ... and he's got the pics to prove it.

Snoop showed off his winnings on Instagram -- toting the garbage bag full of ganja he says he won in a bet he made with a Mexican guy named Lui ... who stupidly picked Canelo to win.

This marks the first time Snoop will smoke Mexican weed since… well, maybe ever.

Despite being so high, he could barely keep his eyes open ... Snoop included a note with the pic:

"Thanks to the champ money may for winning me a pound from my mexican buddy Lui !! U r the pound for pound best! N I'm gonna smoke 2 dat !!! Hahahahahahahah."

Our weed sources tell us ... the average cost for a pound of weed (decent weed) will usually run about $4,000.

So how long will the weed last? Another weed source (we've got a lot of weed sources) tells us ... it would take a talented pot smoker roughly 4 months to puff through a pound of green singlehandedly.

A third weed source (a lesser experienced weed source) tells us ... "There's NO WAY you can smoke a pound of weed in 4 months by yourself."

Hopefully, Snoop will be able to settle the debate once and for all ... as soon as he wakes up.