Jonah Hill told Channing Tatum he had permission to "beat [him] up" if he didn't fulfil his promise of "making him funny" in 21 Jump Street.

The actors star in the big screen reboot of the famous TV crime drama series. The action comedy follows two policemen who are sent undercover to a local high school.

Jonah says Channing's involvement in the film was a thrilling one, and has recalled roping him into doing a comedy picture.

"I called him up and said, Do you want to be the co-star of 21 Jump Street?' We'd literally met at a restaurant once way across the room. I called him and said, Look man, I think it's important that you do this movie, I know you haven't done comedy before, I promise if you do this I will make you funny, and if I don't you can beat me up,'" he told the Kyle and Jackie O radio show.

"I think he walks away with the movie. It's so exciting to see someone do something totally different."

Jonah also serves as a co-writer and co-producer on the movie. The funnyman was reluctant at first because of the stigma attached to remakes, but insists the outcome was a fulfilling one.

"They asked me to adapt it five years ago, but I said I didn't want to remake a TV show into a movie, you always feel like those are going to suck, you kind of roll your eyes when you hear people are doing them. It seems like a cash grab every time I hear about it," he explained.

"And then I thought you know, the idea of going back to the future element, going back to re-live a certain important time period in your life and thinking you have all the answers and then getting back there and realising you have none of the answers.

"To me, that's a cool idea for a movie."