The trouble with the jokes is that once they're written, I know how they're supposed to work, and all I can do is not hit them. I'm more comfortable improvising. If I have just two or three ideas and I know how the character feels, what the character wants, everything in between is like trapeze work.
I've always been fascinated by the difference between the jokes you can tell your friends but you can't tell to an audience. There's a fine line you have to tread because you don't know who is out there in the auditorium. A lot of people are too easily offended.
