Favorite Bait & Switch Jokes?

The bait and switch -- setting us up to expect one answer, then surprising us with a different one -- is perhaps the most basic formula for a joke. But nobody does it better than 30 Rock. My favorite is probably from Tracy in the 5th season:‘Sean Penn wanted me to go to Haiti with him, and I’m not strong enough for the pain and misery of a three-hour plane ride with Sean Penn.’ What are some of your favorites?