The Bridge of Tom and Ray

RAY: Here's the answer. The truck driver could do a lot of things to keep from plunging into the abyss. For example, figuring that his shoe weighs more than a sparrow, he could throw a shoe out the window. But he needn't do anything.

TOM: Wow!

RAY: It's a trick question, what does he do? He does nothing, because in driving from the beginning of the bridge to the halfway point a 20-ton truck is going to consume fuel.

TOM: Oh!
RAY: And it'll easily consume an amount of fuel that's greater than the weight of the sparrow, so when the sparrow lands on the truck, nothing happens. Do we have a winner?

TOM: The winner is Dave May, from Cedar Falls, Iowa. Congratulations Dave!

[ Car Talk Puzzler ]