We sang without hymnbooks at our school and this was in the 70s when conflict in the Middle East was in the news a lot - we had a hymn with a line which I was sure went "and set the damned Jordan free" - when I finally saw a hymnbook and found out it was "and set the downtrodden free" I was disappointed
A childhood belief about hymns

others believed things like this
- When I first heard Matt Monro's song "Born Free," I thought he was singing "Porn Free."Anon
- When i was a tiny lad, I used to think drug free zones were places where you can get drugs for free— Spencer
- I used to think that money from ATM machines were free :p— qwerty
- I used to believe that priceless meant free.— Neo
- I used to think that "priceless" meant free.— DAAA
- I used to believe God had a pet tortoise. There was a hymn we sang that went "Great things he hath taught us"— Lozza