These are the two that I know and have often used to pass the time with friends in the car:
A man walks into a seaside restaurant. After paying the chef a rather large amount of money, the man convinces the chef to prepare him a meal of albatross. After tasting one bite, the man gets up from his table, leaves the restaurant, walks to a edge of a high nearby cliff, and jumps to his death. Why?
[spoiler] The man is one of two shipwreck survivors who were found alive at sea in a life raft. The were not the only two individuals who had originally climbed into the life-raft. While drifting out at sea slowly suffering starvation, dehydration and exposure, other members of the survivor party died. The man was lapsing in and out of consciousness, delirious and weak, when his only surviving companion informed him that the other survivors had died and been thrown overboard. A while later, his companion roused him and claimed to have caught an albatross that they should both try to eat it in order to stay alive. The man chewed and swallowed what his companion fed to him, allowing them both to survive long enough to be rescued.
As the man began to recover aboard the ship that found them, he started to have doubts as to the source of the meat he had consumed while adrift at sea. He vowed that the first thing he would do once reaching the mainland, would be to arrange to eat albatross so that he could compare the taste to what he had eaten on the raft. Once he tasted the chef’s albatross dish, he realized that his survival companion had fed him human flesh to keep him alive.[/spoiler]
A woman wakes up one morning in her high-rise apartment. She takes a shower, eats breakfast, rides the elevator down to the parking garage, and drives to work. Upon returning to her apartment building that evening, she parks her car in the garage, and enters the elevator. She rides the elevator to the 11th floor, exits the elevator, and then walks up 10 flights of stairs to her 21st floor apartment. She repeats the same activity pretty much every day. She rides the elevator down to the parking garage in the morning, and in the evening she rides the elevator to the 11th floor, gets out, and climbs the remaining 10 flights of stairs to her floor. Why?
She is a dwarf, and can only reach as high as the button for the 11th floor in the elevator.