Well, well! I come back to find my thread has grown to 2 pages.
I guess everybody feels strongly about Jeff And The Cheapass. 
To fill in the blanks for those who were wondering, I agree that Chris mishandled the whole thing. I think he should have either
a.) Told the guy he’s up a creek, so that the guy doesn’t come back, or
b.) given the guy the money (or a gift certificate or a T-shirt or whatever) himself, out of the restaurant’s pocket.
But to sic the guy on poor Jeff when he comes in on Thursday seems like bad form to me. Like several people have mentioned, Jeff has probably already spent the money; it’s been a very slow month and we’re all going a little broke, so I’m sure he’ll either have used it for expenses, or treated himself with it by then. Particularly since he’s off today.
Oh, and I recalled something else Chris told me; apparently the money is the guy’s per diem from his company, which is why he wants it back. He gets $40 a day for general expenses like food, and he used all of it on Jeff. (I deal with a lot of business travelers, and many of them like to save their per diems as a way of making extra money, vs. spending them on expenses.)
And yes, as DanielWithrow observed, even Chris told me that he was struck by the guy’s attitude, which is “I’ve been wronged and it should be put right!” vs. “Hey, I’m really sorry, I made a mistake, but I need that money back, if there’s any way you can help me out here.”
The point is, Jeff honestly thought it was a genuine tip, and such tips are not unheard of, so Jeff has done nothing wrong. Particularly since the guy waited several hours before coming back to get “his” money.
And now the customer is making it seem as though Jeff somehow conned him out of his money, and I don’t agree. The person who made the mistake here was the customer, not Jeff.
And for the purposes of fair play, I think if management believes the guy has a point, they should be the ones to reimburse him, either with a free meal, or merchandise, or a couple of drinks on the house, or whatever. I don’t think they should make Jeff give it back…and as Chris said, they really don’t even have a way of doing so.
But I guess I’ll find out tomorrow. 