Hearing someone once use the phrase "Tuesday Week" (to mean a week on Tuesday) as a small child, I became convinced that sometime when I was about 6/7 there was a whole week where every day was a Tuesday.
Even after I figured out what was really meant by it, I still remained convinced this had happened for a long time.
A childhood belief about general

others believed things like this
- I thought the Til Tuesday song said "Books are scary!", rather than "Voices Carry"Anon
- Up until I was ten I believed that Yesterday was a day of the week— Kirsty
- My neighbors used to believe you could never count to 100 in a day, it would atleast take a week.
— raceystacyUS - I thought that "tomorrow" was one of the days of the week— Frank
- I used to want to be a garbage man when I was older because I belived they only worked one day a week— Oscar the Grouch
- I once refused to believe in Thursday. I'd heard there were seven days in a week, but could only name six.Anon