Channing Tatum: ''Jonah just called me up [about 21 Jump Street]. I had never been in a real comedy before, so I was like 'What?' He said it was a comedy, and I said 'Are you sure?' and he was like, 'Yeah man, I got you.' And I said you really have to make me funny because I don't do this stuff, I don't know how to do it. And he promised me he would.''