One of my earliest restaurant memories is having an olive burger at the long-shuttered Village Lantern in Elmhurst. We didn't go out to restaurants a lot when I was a kid, but a few times when my parents took me house-hunting in Elmhurst in the early 60s, we'd sometimes stop at this small nondescript restaurant for dinner. I'd always get the olive burger. That was a long time ago, and I'm not sure I've actually had one since.
Recently, though, I ordered an olive burger at George's and was reminded of all the reasons I think this is a great way to enjoy the all-American burger. My dining companions seemed unaware of this variation on the standard burger, and if you share that innocence, an olive burger is simply a hamburger with sliced green olives on top. Never black olives. You might even want to check before ordering to make sure the olives are, indeed, green. Black ones won't work.
Here's why the olive burger is such a great combination of flavors: The vegetal character of the olives plays a pleasing green note without the additional wateriness that comes from lettuce, and the salinity of the olive provides the only condiment I usually require with beef: salt.
Also, unlike lettuce and tomato, sliced olives provide better traction between bun and burger, so there's no messy slippage: everything holds together well.
I would, however, suggest to George's that they upgrade their olives; the ones on my olive burger tasted just a little old. Not bad, but could be better, and still a very satisfying sandwich, which I would order again.