This, from an interview to promote Bernie:

I'm also excited for the new Charlie Kaufman movie, Frank or Francis. What's it like working with Charlie, and can you tell us anything about your character?

We haven't started formal rehearsals yet, but he's an incredible guy. He's had some ideas about what Francis is like and what he sounds like and what I should study. I can't tell you much about the character though, sorry.

The screenplay satirizes Hollywood, which seems like a dangerous game to play for an actor. Were you tentative about getting involved?

No, I'm all for it! That's what made me extra into it. It's necessary and it's profound. Our country is super celebrity-obsessed and the world, especially the United States, really needs a movie like this to examine our need to be famous. (Source)