Physics and golf? You must be joking

Whenever my friends find out that I did a PhD on golf-ball impacts, they think I'm joking. I remember arguing long into the night at a dinner party with a woman who just would not believe me. Every half an hour or so she would say, "Go on, tell me, what did you really do?" It's funny how people come up with the same joke, and then think it is the first time you have ever heard it: "I suppose it's a load of balls then."