Hmmm, I assume the usual hamburger/hotdog isn’t what you’re looking for.
I think the least common thing I put ketchup on is kraft mac n cheese. Don’t do it every time, but every now and then, when I’m having the standard, package only mac n cheese, I’ll put a dab on there.
Can’t use much, or it sucks. But the kind of amount you might drop as you’re taking a bite of something else, that works great. That’s how I found out I liked it, back as a kid.
I will put ketchup on mac & cheese, of any kind, no matter how old your grandmother’s recipe is. did it right in front of my Italian potential mother-in-law too, there are certain things that have to be established early in the relationship.
The night before I mix two eggs with a little milk and put it in a microwavable mug. Then microwave it for 30 seconds, stir and repeat twice. It creates a round slab of egg that I put on a piece of buttered toast with ketchup spread on it.
Chicago dogs are their own thing, though. The rest of the ingredients other than the mustard have a combined flavor profile similar to ketchup: ketchup is basically a poor man Chicago dog.
Also, their poppy sees hot dog buns are a weird pick.