Via a commenter on Atrios whose name I failed to take down.
A New Yorker in a bar turns to the man next to him during the RNC and asks:
"Do you want to hear a dittohead joke?"
The man answers:
"Before you tell it you should know that I'm a dittohead and so is the man next to me and so is the man next to him. Do you still want to tell the joke?"
"Nah" says the New Yorker.
"I don't want to explain it three times."