I’m watching the episode, and it has one of those jokes that I love more than anything. I call them the “sucker punch” jokes. They come out of nowhere, are usually way out of bounds, and I usually can’t breathe afterward.
It sets up like this: Guest voice James Woods (as himself) comes back to ruin Peter’s life by stealing his identity. It’s a long story, but then Peter gets the idea to ruin Woods’ reputation by becoming him. So he goes on Letterman as James Woods and proceeds to promote his new movie “September 11, 2000-FUN!” starring woods “as a window washer who has just cleaned the last window of the World Trade Center only to turn around and see, you guessed it, a plane coming toward him”. The crowd predictably reacts with “boos” and Letterman tells him that sounds horrible. (So I like sick humor, and I am already laughing). Then Peter adds “It’s sort of old-time humor. Like two pies in the face. And one in a field in Pennsylvania.”