My family moves a lot because my dad's in the military, and it was about 1996 (I was 6 then) when we moved to Manitoba from Nova Scotia.
My parents made coffee with the coffee machine that was supplied in one of our hotel rooms. I heard them discussing it. My dad made a face at the coffee and stated, "I got the grounds". Little did I know that my parents use the term "the grounds" for when the coffee doesn't filter properly and you get coffee grounds in your cup.
Well, I thought The Grounds was a disease, and in my six-year-old mind, diseases were always fatal. I wondered why my mom and dad were so calm about my dad having such a horrible illness. I vowed never to drink coffee because I did not want to end up in the hospital, let alone dead, from a case of The Grounds.
My parents still say "I got the grounds", and I still haven't told them my beleif. I now enjoy coffee, and I'm still alive evough to be typing this. Hahahaha.
A childhood belief about drinks

others believed things like this
- I always refused to eat coffeecake because I thought it was made with coffee grounds. Anon
- I used to believe that the term "being mugged" meant someone beat someone else with a coffee mug.— Matt Thiel
- I used to think it was illegal for children to drink coffee— C.W.
- I always thought there was a drinking age for coffee, because it was an adult drink like beer and wine.Anon
- I used to believe that coffee was tea with milk in it.Anon
- I thought you could get toffee from mixing tea and coffee.Anon