Seth Rogen is known as the ultimate Hollywood stoner, and if you've ever seen any of his comedies, it's pretty clear that his co-stars typically get in on the action within the film. However, what many don't realize is just how much smoking goes on off-screen as well. Joseph Gordon-Levitt has been lucky enough to star alongside Rogen in two different films now, and he's figured out the hard way that smoking pot doesn't always get the creative juices flowing as nicely as it does for Rogen.

The two first worked together on "50/50" and are now promoting their latest stoner Christmas movie, "The Night Before," which also stars Anthony Mackie. While talking about the film on Wednesday night's episode of "Jimmy Kimmel Live," Gordon-Levitt revealed what it's really like working behind-the-scenes with the king of marijuana (who he does a perfect impression of, by the way).

"We're all throwing in ideas to the script at the last minute, and there is definitely a joint being passed around the room starting early in the day," the 34-year-old actor told Kimmel of the movie-making process with Rogen. "The first day I said like, 'Oh, I know how to smoke. I've smoked since I was a kid. I can do this, sure. Let's see! It'll inspire good comedy.'"

Turns out, all of his pot-induced ideas were only funny to him, but he did have some great advice for those who do like to light up. "So I decided to start smoking at the end of the day, after the work was done," Gordon-Levitt said. "Smoke at the end of the day, kids, wait until the day's work is done. Then enjoy your weed."

Catch the two in the hilarious new Christmas movie "The Night Before" when it hits theaters Nov. 20.