It occurred to me in my junior year of high school. I got my first letter from a big college. I still have that letter to this day - a letter from Indiana.
The news of the discovery spread fast all over the country, and inquisitive enquiries mingled with congratulations from this moment became the daily programme.
A joke is not a thing but a process, a trick you play on the listener's mind. You start him off toward a plausible goal, and then by a sudden twist you land him nowhere at all or just where he didn't expect to go.

