I was always stumped with this when I was younger: I knew that Chinese people ate with chopsticks and that American people ate with forks, and I remember thinking that if Americans used those miniature forks to feed their babies what did Chinese mothers use? Toothpicks? Twigs?
Some of you might have heard this elsewhere as a joke, but I assure you that I really thought it. ;)
A childhood belief about nationalities

others believed things like this
- I used to believe that if you touched Chinese people, they would break.— Christian
- i used to believe that euthanasia has something to do with young chinese people— CW
- I used to think that I nursing home was a place were mothers would take their new born babies to feed them— Katie
- When I was younger, I believed that the Chinese Mann Theatre was built in honour of Bruce Lee.— glenys
- For the longest time I thought that Rudolph the Red-Nosed Reindeer had a very "chinese" nose...Anon
- There was a Chinese takeaway near us called the Orient Express. I thought it was Onion Press. Yeah.— Spook