James Franco gave Bryan Cranston a marijuana painting.

James Franco

James Franco

The 38-year-old actor created most of the artwork seen in his character's home in 'Why Him?' and gifted his co-star a "beautiful" picture of a marijuana leaf, but had mixed the drug in with the paint he used.

Discussing the art in the film, he said: "I did a lot of them, yes.

"There was supposed to be a lot of art in the house, and they consulted me, 'What kind of art do you think you would have?' They showed me kind of very generic paintings, so I thought, 'Well, I have some paintings that may be funnier and may be more in line with the character.' "

While Bryan, 60, thought the marijuana leaf painting was "beautiful", his wife Robin Dearden wasn't so impressed.

Appearing on 'Conan' alongside James, he said: "It was a beautiful painting of a marijuana leaf... He actually painted it with real marijuana in the paint...

"I brought it home to my wife. We've been together for almost 30 years, and we have a nice little Connecticut home, and I said, 'Honey, where do you think this would fit?'

"And she said, 'I don't know if it would fit anywhere.' "

But his co-star had a suggestion.

He quipped: "Over the bed."

Also on the show, James showed off one of the pieces of his art, which was called 'Humping Capybaras', depicting two of the rodents - but admitted he had initially made a mistake.

He said: "I got it wrong. I thought they were hamsters, so it was 'F' word hamsters, and then I put it online and everyone was like, 'No, those are capybaras.' So I PG'd it up."