Is my word of the day. Basically it’s a phrase in which the last bit makes you reframe the first bit. The examples on the Wikipedia page are brilliant, and of course feature the master of the genre, Groucho Marx:

• Where there’s a will, I want to be in it.
• The car stopped on a dime, which unfortunately was in a pedestrian’s pocket.
• “If you’re not part of the solution, you’re part of the precipitate.” — Henry J. Tillman
• “Onward he came, and his feet were shod with his—chilblains.” — Aristotle
• “I belong to no organized party. I am a Democrat.” — Will Rogers
• “I’ve had a perfectly wonderful evening, but this wasn’t it.” — Groucho Marx
• “Time flies like an arrow; fruit flies like a banana.” — Groucho Marx
• “I want to die like my father, quietly, in his sleep—not screaming and terrified like his passengers.” — Bob Monkhouse
• “A modest man, who has much to be modest about.” — Winston Churchill
• “If you are going through hell, keep going.” — Winston Churchill
• “I haven’t slept for ten days, because that would be too long.” — Mitch Hedberg
• “I don’t have a girlfriend, I just know a girl who would get really mad if she heard me say that.” Mitch Hedberg
• “Take my wife—please.” — Henny Youngman
• “It has been said that democracy is the worst form of Government except all those other forms that have been tried.” — Winston Churchill
• “You can always count on Americans to do the right thing – after they’ve tried everything else.” — Winston Churchill
• “I weigh 135 pounds naked, if that scale at the train station is to be believed.” — Emo Phillips
• “I’ve never seen him so sad, or ever before.” — Scruffy in Futurama
• “If I could say a few words, I would be a better public speaker.” — Homer Simpson