Yeah, in optical shops to work as an optometrist. We had this deal to go for Saturday and/ or Sunday from 12-6, they'd give us $300 cold cash, most of the time we sat there and read the newspaper (my preference) or the academy series books. Had to do about 10 refractions every time, and talked on the phone and read the newspaper the rest of the time.
I stopped doing it because I wanted my free time to myself, but if you're strapped for cash it's a great deal.
Be careful about moonlighting doing MD work b/c you might not be covered by malpractice insurance.