I used to believe that the stereotypical politeness of Far Eastern Asia was because everyone there knew martial arts. Logically, you would never be rude to anyone in case they'd kick your ass.
A childhood belief about nationalities

others believed things like this
- That "martial arts" had something to do with marriage. — Mike Lewyn
- that the smallw arts on my dads neck were caused by swearing!— steve
- For along time I thought the Middle East and Eastern Europe were just different names for the same place!— Helllowerer
- I used to believe Germany was in Asia somewhere near Russia.— It's in Europe!
- When I was young I used to believe that Euthanasia was a youth movement in Asia- how naive is that!!!— Ruth
- I used to believe that "euthenasia" was "youth in Asia", and I couldn't figure why that was A Bad Thing.— Kellye