I was just fooling around with the piano and Todd [Phillips] was like, 'Hey there's a great spot in the movie [The Hangover] where we need a little bit of a breath in the narrative. You should write a song and stick it in there.' And I was like, 'Well, what should the song be about?' And he said, 'The tiger.' 'Oh, okay.' So I went off and I wrote this song. I came back and Todd and I tinkered with it a little more and then we shot it right then. It all happened in a day.

I'm working on a script right about Civil War re-enactors who go back in time to the actual Civil War. It's kind of a big, crazy Back to the Future comedy. So, of course, it's the Civil War - I play the banjo. I was just having a conversation with one of the producers about some of the material and he was like, 'You know, we have to work in a scene where you play the banjo. And I was like I'll get behind that.

When you're playing a fictional character reacting to the real world, it's incredibly difficult and confusing and kind of messes with your values a bit.

People who grew up in New York City or Los Angeles tend not to even understand what goes on in the rest of the country. I'm really glad to have grown up in an environment where I actually was kind of a weirdo because I was obsessed with comedy and movies and stuff.

I loved the show Lost, in part because the writers were so nimble in how they would take things from previous episodes, that probably weren't created with any intent towards a larger narrative, and they would get woven into narratives in a really elegant and exciting way.

We did some camera tests blacking it out, we made a prosthetic with a gap in it, but that made me look like a donkey, so I vetoed that right away. And then I just finally called my dentist and said, 'You know, I've had this implant for 20 years. What's it involve in taking it out?' And he said, 'It's actually not that big a deal. We can do that.' So we took it out and I was toothless for three months, for the run of the movie [ The Hangover] .I take my job very seriously.

I found myself often asking the question, "Who deserves to be made fun of?" Depending on your mood, the answer can be no one or everyone. It took me a while to understand the math of how those field pieces came together. I don't think that ridicule is ever funny, but there are times when that gets the biggest response.