I have never heard of peanut butter on hamburgers, never considered it, never heard it mentioned, never seen it, never want to try it. That is nasty.
Hell, I'm still waiting for one of the big chains to come out with a hamburger with a fried egg on it.
Not sure if you were serious or not, but Red Robin has a burger with a fried egg on it, as well as bacon, cheese, lettuce, tomatoes, and mayo. I didn't think I would like it but it is actually really good, it's the only thing I order there anymore. It's called the Royal Red Robin.