Somebody started a thread like this recently, but I'll be danged if I can find it. Anyway, the idea was to take a statement and alter it by inverting the order of the words. I think.

This one comes from boxing hall of famer Bert Sugar, regarding the signs now posted on the doors of Las Vegas hotel rooms.

The signs say:

Have you left anything?

Mr Sugar would change them to:

Have you anything left?