Replacing anyone in Show/Movie

Out of the top of my head I don't know why but it would be fun(ny) replacing Will Smith in the movie Hancock. I would have fun beating some sense into the bad guys and living as a hot black immortal super human. Besides the matter of fact that he has technical vocab, I think it would be as funny being the character as it would be watching it. It would be amazing to think that I would be in a movie that was so funny it made Chris crap his pants while watching! It would be an experience I would never forget. I would quote it every day and still laugh so hard I would start crying. Well it was a so and so commical movie, I would love starring in it.