Cat in a Box
Q. How many cats can you put in an empty box?
A. One. After that, the box isn’t empty anymore.
Q. A man is washing windows on the 25th floor of an apartment building. Suddenly, he slips and falls. He has nothing to cushion his fall, and no safety equipment—but he doesn't get hurt. How is this possible?
A. He's washing windows inside the building.
Source: Twenty Two Words