Matthew McConnaughey has revealed that Snoop Dogg 'tricked' him into smoking real weed during filming on their forthcoming stoner comedy The Beach Burn, in possibly the least surprising on-set jape in movie history.

McConnaughey and Snoop were shooting a scene in which McConnaughey's character, Moondog, is searching for some weed to clear his writer's block. Obviously, the man with the magic weed is Snoop.

"I went to the prop man to make sure I have the prop weed which is like crushed oregano," McConaughey told Jimmy Kimmel. "[During filming], we pass back and forth and all of sudden at the end he goes, ‘Yo Moondog, that ain’t prop weed, that’s Snoop Weed.’ I was like, ‘Oh you son of a a gun.'"

It doesn't sound like the rest of the day was particularly productive.

"The next nine hours were a lot of fun but I don’t think we used one word in the English language," McConnaughey said.

NINE HOURS. Somehow - despite Snoop's apparent mission to swap all props on the set for joints - they got the film done.

The Beach Burn doesn't have a solid release date yet but it'll be out before the end of the year and features Jonah Hill (of course), Isla Fisher, Martin Lawrence and Zac Efron - as well as being directed by Spring Breakers director Harmony Korine.