In one of Dave Barry's columns he declares that the only appropriate response to:
Does this dress make me look fat?
is for the questionee to stick a fork into one or both eyes. Much less painful than answering…

I have taken this to heart, and whenever my wife lets slip an unanswerable question I holler:

Where's my fork?!
She cracks up, I dodge a bullet, and innocent bystanders are spared potential unpleasantness.

Kudos to Dave.