A self-reinforcing meme, I'd imagine. The more you hear it, the more you're likely to use it as an example. I've certainly used the phrase "dentist from Ohio" a

A self-reinforcing meme, I'd imagine. The more you hear it, the more you're likely to use it as an example. I've certainly used the phrase "dentist from Ohio" a few times myself — no offense meant to dentists and Ohioans.