As a child, I was really confused about restaurants that advertised "All you can eat". It is, after all, an ambiguous phrase. It made me think that there must be SOME restaurants where a group of people might go, only to be told for some mysterious reason "Only some of you can eat here.", or "Not all of you can eat here." But those that advertised "All you can eat" must be telling you that they weren't that kind of restaurant, saying that "All you can eat here (not just some of you)".
A childhood belief about excursions

others believed things like this
- I used to believe that commercials would only go away when you bought the product that was being advertised.— Hayabusa
- I used to think that if a movie was advertised on the side of a bus, that meant it was really good. — Aretia
- My cousin thought ribs at restaurants were people ribs.Anon
- I used to think all Italians worked in pizza restaurants.Anon
- I usd to believe that at restaurants that had a BYO sign out the front, you had to "bring your own" meal.— Fiona
- I always thought that duck sauce (from chinese restaurants) was duck poop.
— emily