I used to believe that pink lemons were used to make pink lemonade. I once saw them in an ad for a particular brand of lemonade and believed ever forth that they existed and I just couldn't find them anywhere.
A childhood belief about general

others believed things like this
- I thought pink lemonade came from pink lemons.Anon
- I used to believe you could pour lemonade in a pan, put it in the oven and make lemonade cake.— wumpmugg
- i knew that if you ate beets your urine would turn pink and i thought if it was pink, then you could drink it.— JP
- I believed that 4 p.m. was pink, and 5 p.m. was blue. I don`t know why.— blue
- I believed that ham was mouse meat, because it was pink and my dad told me so. — Zo
- I thought Pink's "You make me sick" was "you make me sick, you make me look like a candlestick" LOL— Rice