An email from a friend contained the definition and a bunch of paraprosdokians. I added some from notable figures at the end, courtesy of Wikipedia:

A paraprosdokian sentence consists of two parts where the first is a figure of speech and the second an intriguing variation of the first. They’re used typically for humorous or dramatic effect. Enjoy these!

* Never argue with an idiot. He’ll drag you down to his level and beat you with experience.

* Going to church doesn’t make you a Christian any more than standing in a garage makes you a car.

* If I agreed with you we’d both be wrong.

* We never really grow up, we only learn how to act in public.

* Knowledge is knowing a tomato is a fruit; Wisdom is not putting it in a fruit salad.

* The early bird might get the worm, but the second mouse gets the cheese.

* How is it one careless match can start a forest fire, but it takes a whole box to start a campfire?
* Dolphins are so smart that within a few weeks of captivity, they can train people to stand at the edge of a pool and throw fish.

* I didn’t say it was your fault, I said I was blaming you.

* Women will never be equal to men till they can walk down the street with a bald head and a beer gut and still think they’re sexy.

* A clear conscience is usually the sign of a bad memory.

* You don’t need a parachute to skydive, but you do need one to skydive again.

* The voices in my head may be fake, but they have good ideas!
* Hospitality is making your guests feel like they’re at home, even if you wish they were.
* I scream the same way whether I’m about to be eaten by a shark or seaweed touches my foot.
* Some cause happiness wherever they go, others whenever they go.
* There’s a fine line between cuddling and holding someone down so they can’t get away.
* You’re never too old to learn something stupid.
“He was at his best when the going was good.” —Alistair Cooke on the Duke of Windsor[1]
“There but for the grace of God— goes God.” —Winston Churchill[1]
“If I am reading this graph correctly—I’d be very surprised.” —Stephen Colbert[4]
“You can always count on the Americans to do the right thing—after they have tried everything else.” —Winston Churchill[4]
“If all the girls who attended the Yale prom were laid end to end, I wouldn’t be a bit surprised.” —Dorothy Parker[4]
“I’ve had a perfectly wonderful evening, but this wasn’t it.” —Groucho Marx[5]
“A modest man, who has much to be modest about.” —Winston Churchill[5]
“She looks as though she’s been poured into her clothes, and forgot to say ‘when’.” —P. G. Wodehouse[5]
“I like going to the park and watching the children run around because they don’t know I’m using blanks.” —Emo Phillips[5]
“If I could say a few words, I’d be a better public speaker.” —Homer Simpson[6]
“I haven’t slept for ten days, because that would be too long.” —Mitch Hedberg[3]
“I sleep eight hours a day and at least ten at night.” —Bill Hicks[3]