My sister's friend thought that a "Hard" drink meant it was extra sweet. She drank a bunch of 'Mike's Hard Lemonade' without noticing.
A childhood belief about drinks

others believed things like this
- I used to believe you could pour lemonade in a pan, put it in the oven and make lemonade cake.— wumpmugg
- At about age 7 I thought one could see the people running around on a map, if one looked hard enough.— Adam Smith
- I used to believe that "unsavory" meant "sweet".— unsavory
- when i was abotu 5 or 6 i thought that if i were to pull hard enough on my pants, i would float away— Aaron
- --I thought if I swung hard enough in my swing i could possibly reach an airplane
— dusty chenille - I thought farting was magical wind, and if you did it loud and hard, you would be able to move yourself.— Blake