Lateral thinking puzzles

To practise question forms, lateral thinking puzzles can be fun. Example:

A man is replacing a wheel on his car, when he accidentally drops the four nuts used to hold the wheel on the car, and they fall into a deep drain, irretrievably lost. A passing girl offers him a solution which enables him to drive home. What is it? [Answer in "comments", below]

More: 101 lateral thinking puzzles

They make good classroom activities apart from anything else because your learners really want to form those questions!

I suggest you refuse to answer any questions that are incorrectly formed... ("Good question, but if you can correct it, I'll answer it...")

Note that lateral thinking puzzles tend to be a bit morbid (and death is a subject I think best avoided in a classroom). The ones here are bit less morbid.