Here's one more Japanese superstition that I've heard of but was not mentioned in your culture class on meishin.
When you sneeze, it's because someone somewhere is talking about you.
I don't know if this is an actual superstition or not, but it's what I've heard.
Can anyone confirm it? I'm pretty sure I've seen it happen in anime before. Some one says something disparaging about someone, and a short clip of them sneezing is shown.