It's a tradition in my family to watch the movie "A Christmas Story" during the holidays. There is this one scene where Ralphie, the kid, is helping his dad change a flat tire and he drops the hubcap he was holding the screws from the tire in, and he goes, "Oh fuuuuuuudge." His parents got really upset and his mom put a bar of soap in his mouth. So for a short time in my young life, I believed that in a different context, the word "fudge" was a cuss word.
It was only later, when I was about fifteen, that I realized what Ralphie was SUPPOSED to say, and that it couldn't be said in a PG-rated family Christmas movie.
A childhood belief about swearing

others believed things like this
- I was told that for every christmas carol i sang before christmas time santa would give me one less present!— K
- when i was little i believed that when we watched a movie people had to act the movie all over a gen.
— Emmer - i used to think that the word "stupid" was a curse word, ranging in scale right beside the "f" word.Anon
- I used to think the word "european" had something to do with pee, and that kids weren't supposed to say it.Anon
- When we were young, the adults said that the rudest possible word was 'District Nurse'. And we believed them— Steve Haughton
- I used to believe that EVERYTHING we did was being filmed for someone somewhere to watch as a movie— KatBird_27