Hilarious... from the classic episode: Lisa goes Vegetarian:
"...is it true you were the driving force behind Lisa Simpson becoming a vegetarian in 1995?"
Howard Lyman: "Well, "driving force" I don't know, but I was probably the catalyst at the time that made it happen. I did a lecture at Cassandra Peterson's living room (she's better known as "Elvira"). One of her friends said to me afterwards: "My name is David Mirkin. I'm the executive producer of The Simpsons. If I put 40 writers in a room, would you talk to them?" I said sure. So he did, and we had a wonderful evening—I mean, some of the brightest minds you ever saw in your life. He then flew to England and got together with Paul and Linda McCartney, and they did the show on Lisa becoming a vegetarian. Many of the things that you see in that show, at least to me, are direct offshoots of what I had said in the lecture. David Mirkin, on the night I first met him at Elvira's, was a carnivore. Today he is my friend, and he is a vegan." Quote from here.