You probably know actor James Franco best as the star of stoner comedies like Pineapple Express (2008) and action films like the Tobey Maguire Spiderman movies. But did you know that he also paints - with cannabis?

Last week, Franco and fellow actor Bryan Cranston sat down for an interview with Conan O'Brien to promote Why Him? - a holiday rom-com about a dad (Cranston) dealing with his daughter's obnoxious billionaire boyfriend (Franco). To complete Franco's character, set decorators wanted to cram his home full of artwork, including many of Franco's own paintings.

But the best of the bunch didn't make it onscreen. Franco gave one to his co-star as a present - much to the dismay of Cranston's wife.

"It was a beautiful painting of a marijuana leaf," Cranston said. "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.' "

"Over the bed," Franco suggested.

The best part of the gag is that Franco actually mixed cannabis leaf into the paint to give the piece an extra bit of authenticity. Check out this clip for a peak at the leaf portrait as well as Franco's other masterpiece - a pornographic painting called "Humping Capybaras."