What are "Paraprosdokian's"?

If you don't know you're not alone. However, you are missing out! Hopefully this will enlighten you (alongside providing quite a few laugh's!)...

A good friend recently sent me a list of "Paraprosdokian's - a figure of speech in which the latter part of a sentence or phrase is surprising or unexpected;" As you can never laugh in life enough I will pass along some periodically. Please enjoy and here's the first...

"Do not argue with an idiot. He will drag you down to his level and beat you with experience."

PS - As per sources I have bee unable to find any, but want to make it clear and credit whomever may have come up with these. Very funny!