After drawing about 7,000 Dilbert comics, you might wonder how many times this has happened before. My best guess is that is has happened at least 70 times, some instances more egregious than others. That's because there are only about 100 different jokes in the universe. All jokes are rehashes of something that came before. The best you can do is disguise them.
It makes me wish I had been born around 1,900 B.C. when the first great innovation in humor was invented: the fart joke.
After that, every seemingly new fart joke was nothing but a rehash. I've used the fart joke several times in Dilbert, with just enough subtlety to get published. Here's one
The joke in both Dilbert comics is about 4,000 years old. And that assumes the Sumerians didn't steal the joke from someone else.
My strip that runs today (August 1, 2008) is only a second cousin to the fart joke, and maybe the naughtiest thing I ever got away with.