This is driving me nuts. I can see, in my mind’s eye, the listing “Naked Burger” on a menu. It’s a burger either with no trimmings, or perhaps with no bun. I know it’s not at Red Robin, because that’s where I was trying to order it, and the waiter said “Come again?” and I looked at the menu and there it wasn’t. Can’t find anything on Google. Perhaps it was discontinued?
Meanwhile, here’s a video I found while I was searching for “naked burger.”
I am in the middle of reading the novel This Book Will Save Your Life, set in LA, and IIRC it mentions the protagonist eating a Naked Burger from In-n-Out.