From today's AVWeb Newsletter:

Short Final...
A pilot was flying in his C-205 with his two sons, ages 4 and 6, over the mountains of Tennessee, bucking a strong headwind. He looked in the back and noticed the boys looking down in the valley below, where a train was also heading northwest, and they were barely gaining on it. Nothing was said.

Four months later, the younger son, Brian, was called to kindergarten roundup, where the officious school psychologist was conducting evaluations. When Brian's turn came, the shrink said: "Brian, what color is an apple?" Brian replied: "Are you talking about the inside or the outside of the apple?" Perplexed, the shrink went on: "Well, Brian, which goes faster, a train or a plane?" Straight-faced, Brian replied: "Well, Doctor, it kind of depends on the headwinds."