"Are you trying to be funny?" - my Dad reckons that's about the worst.
Some of my faves:
1. Dorothy Parker was always good value, saying about Katherine Hepburn, "She runs the gamut of emotions from A to B", and in a book review, "This is not a novel to be tossed aside lightly. It should be thrown with great force."
2. "He inherited some good instincts from his Quaker forebears, but by diligent hard work, he overcame them."
said by someone I don't know or can't remember, about President Nixon
3. A Victorian one:
""He uses statistics as a drunken man uses lamp-posts; for support, rather than illumination"
4. "He has all the virtues I dislike and none of the vices I admire"
Churchill
5. And, about an actor, "he played The King as if someone was about to play the ace"