Riddle: There is a one-mile bridge that can only carry a 25-ton truck on it or it will break. Fred is driving his lumber truck which weighs exactly 25 tons before it goes on the bridge. When Fred is 3 quarters of the way across the bridge, a small bird lands on his truck. However, the bridge doesn't break. Why is that?
Answer: Fred's truck will have used more fuel than the weight of the bird, and will therefore be under 25 tons.