Comedy takes something expected and twists it to prompt a surprise. For example, Bill Maher's joke in March, when Cheney saw a doctor about leg pain: "Do you stretch?" the doctor asked. "Are you kidding?" Cheney said. "I linked 9/11 with Saddam Hussein!"
Beyond the smile, I love a twist's illumination of character and voice. Consider this, from an e-mailer to Suzanne Beecher's Dear Reader book club, about a time she was baking with her mother: "I asked my mom if I could have a job. She gave me some suggestions, and then I told her, 'I mean an eating job!' "
For me, the hard part is taking a sentence less literally ... learning to recognize a springboard word.