I grew up in a ranching/farm family. One time we were running cattle through a chute to put fly spray on their backs and one kicked me through the fence. I was outraged and yelled "OW! You cock sucker!" To me a cock was a rooster or chicken and a sucker was a foolish person or an idiot. I thought I was saying you idiot chicken. Even after I got into trouble, I still didn't know why what I said was bad until years later.
A childhood belief about swearing

others believed things like this
- I thought that "cocky" was a bad word since it has "cock" in it— Shimmer
- When I caught chicken pox, I thought it was down to me eating too much chicken.— Helen
- In my youth,I was always convinced that my chocolate easter eggs came from my uncles chicken farm!— Jamsie
- I used to believe that if you buried a chicken bone in the backyard it would grow a chickenAnon
- I thought that eating chicken gave me muscles (chicken and muscles sound the same in Mandarin).— NG
- I used to believe that all meats were chicken. I called everything chicken. :)— Girlfloyd