Then, one day, I got this one, which I did not understand:
Ken Thompson has an automobile which he helped design. Unlike most automobiles, it has neither speedometer, nor gas gauge, nor any of the numerous idiot lights which plague the modern driver. Rather, if the driver makes any mistake, a giant "?" lights up in the center of the dashboard. "The experienced driver", he says, "will usually know what's wrong.
I now know that Ken Thompson was one of the creators of unix. In this fortune, the car is unix, and the giant '?' is the dreaded 'segmentation fault' error that plagues beginning unix/C programmers and which provides no useful information.
I have always felt a little bit bad for him, being teased in this way (and why does Dennis Ritchie get off so easy?). Apparently, though, Mr. Thompson and I work at the same company now, so maybe I will have a chance to comfort him.