I used to think that the song from CATS ("Gelical cats!") actually went "Genital cats!" I thought Genital Cats was like, another euphemism for crabs or soething, because the song went, "Genital cats are black and white. Genital cats are rather small...."
A childhood belief about misheard lyrics

others believed things like this
- I alwaysused to think white cats were girls, and black cats were male ...— Smiley Face
- I used to believe that the cats eyes in the road...reflectors...were the eyeballs from real cats.— Liza P.
- My sister and I thought cats and dogs were the same animal, the dogs were male and the cats were female.— Paul
- I used to believe all dogs were male and all cats were female. I still call dogs "boy" and cats "girl." — Kelly F.
- I use to believe that cats and dogs were the same species; cats were girls and dogs were boys.— poopcrystals
- My sister's friend thought cats were just small dogs when she was younger.— Richard Davies