I've often started off with a lawyer joke...

I've often started off with a lawyer joke, a complete caricature of a lawyer who's been nasty, greedy, and unethical. But I've stopped that practice. I gradually realized that the lawyers in the audience didn't think the jokes were funny and the non-lawyers didn't know they were jokes.

This joke is a little bit hard to classify. The crux of the humor lies in making fun of lawyers. Apparently, in the mind of the teller, everyone who is not a lawyer believes that lawyers are nasty, greedy, and unethical, and everyone that is a lawyer is not able to derive humor from jokes that insinuate that they are the aforementioned things.