PARAPROSDOKIAN - A paraprosdokian ( /pærəprɒsˈdoʊkiən/) is wordplay where the latter part of a sentence or phrase is surprising or unexpected in a way that causes the reader or listener to reframe or reinterpret an earlier part. A really good example where the word "right" changes meaning as the sentence is completed;
* War doesn't determine who is right only who is left.
Now in common use the word is from an unknown author possibly 19th century, who mashed up the Greek for παρά (para, “against”) and προσδοκία (prosdokia, “expectation”). There is a lot of criticism of the words origins by purists and despite being in common use, it has not yet been added to a paper dictionary.
* If I agreed with them we'd all be wrong!
It is frequently used for humorous or dramatic effect, sometimes producing an anticlimax. For this reason, it is extremely popular among comedians and satirists such as Groucho Marx;
* Time flies like an arrow, fruit flies like a banana.
See more at http://www.paraprosdokianfun.com/