Once I asked my mom what the little specks flying around in a ray of sun shining through the window were. She said it was "flying dust". I misunderstood, and thought she said "flying dogs". For years, I imagined these microscopic cats and dogs flying around in rays of light.
A childhood belief about cats and dogs

others believed things like this
- I thought the flying buttresses on a cathedral actually enabled it to fly somehow!Anon
- I always thought the connectors on the telephone lines were flying turtles.— Angie B
- I used to believe airplanes were flying submarines.— Gullible isn't in the dictionary
- I used to believe that aeroplanes could reverse when they are flying. Anon
- i used to think technology was "flying cars" and that we would have them by the year 2000.— josieg
- i used to belive that god was a giant police man flying around the earth— sam