Whenever there's leftover pizza to reheat, on top I'll put chopped shallots that were soaked in olive oil, prosciutto, ultra-thin slices of fresh serrano chilies. If I have it, sometimes I'll substitute the prosciutto with thinly-sliced hard salami.
In a way, that's taking fast food and making it into my own thing.

Sometimes I'll bring a burger and fiddle with it the same way, like putting sharp cheddar on it and melting it at a low temperature on the toaster/oven. At the fast food place, I ask them to hold the condiments, so the bread doesn't get soggy before that.

If it's a more upscale burger - higher quality meat - I ask them to hold the tomato and onion, at home I'll substitute with yellow heirloom tomatoes with a spoonful of the shallots heaped on top.
Or I'll caramelize a full onion and put that in instead.

To top it all off, recently my wife pickled a large jar of sliced yellow beets.