I used to believe that when I bought a product tested 100 times, it meant that the stuff i was buying had actually been tested 100 times and I wondered why it didn't wear out and was expecting it to fall into pieces very soon.
Took me years to realize my mistake. I am a bit slow.
A childhood belief about going shopping

others believed things like this
- I use to think that alka seltzer tablets were instant 7UP soda until one day I tested my belief. — aj
- I used to believe that if you played a record too many times it would wear it out.— April
- I used to believe that commercials would only go away when you bought the product that was being advertised.— Hayabusa
- I used to believe that comercials are evil beings that would keep appearing until you bought the product.Anon
- I used to think that "One, two, three times a lady"
was: "one, two, three times related"Anon - I used to believe making a cake from scratch meant using a box mix rather than buying a cake from the store.— EZ