When I was seven, my uncle, who lived upstairs from us, brought home a puppy, which he eventually gave to my sister and me. He and my aunt said it was "part dalmatian and part travelling salesman," so for years I thought there was a breed of dog called a travelling salesman. I wondered why I never saw any reference to it anywhere. I figured it out when I was around twelve and started hearing those jokes.
A childhood belief about cats and dogs

others believed things like this
- when I was little my uncle told me he was part bear. I believed people could be part bear until I was twelve. — Audrey
- I thought that a travel visa was a special credit card which was used for travellingAnon
- I thought that a "student visa" meant to use a credit card while travelling.Anon
- i used to think that moths were travelling to different worlds when they circled the lights— Amanda
- I believed that the breed of dog called Boxer was called that because they could stand up and box.Anon
- I used to think Uncle Ben and Aunt Jemima were a married couple. — l stu electtirc boogaloo