Paper towns. As in, towns that only exist on paper. There’s also a movie with that name, Paper Towns, though I can’t recall if it’s related to the concept. IIRC, it mentions the term at least. It’s absolutely true. Back when paper maps were a thing, they would put some random town in, and look for it in competitors’ maps.

Now that we have satnav, things like Google/Apple Maps and various others, I think they’re mostly a thing of the past.