When I was little, I would see calendars that had the letters "SMTWTFS" on the top. Whenever I saw these calendars, I figured that SMTWTFS, one word, was a company that made calendars, and not an abbreviation for the days of the week. One day I said to my mom, "Wow Mummy, smitwiffs must be a really big company! They make calendars EVERYWHERE!" My mum is still laughing to this day.
A childhood belief about spelling

others believed things like this
- I thought that the insurance company Aflac was owned by Ben AffleckAnon
- I used to think that a company had boats all over the world making waves, and airplanes making cloudsAnon
- From the first six letters of this word, I thought that “megalomania” had something to do with megalodons.— Enrico
- I thought that "tomorrow" was one of the days of the week— Frank
- I once refused to believe in Thursday. I'd heard there were seven days in a week, but could only name six.Anon
- I always thought that after 1999 it would be 1990 again, but with different months and days of the week
— optional