I thought that Left Luggage at a railway station was on the left hand side and I never figured why there was no right luggage. I finally twigged when I heard the expression when I was in my twenties!
A childhood belief about trains

others believed things like this
- I used to hold my hand over my hair whenever i left the house and it was windy incase my hair blew away— lisa
- I used to believe that "pork chops" were called "port chops", and came from the left side of the pig.Anon
- I thought the only countries that drove on the left was UK and Hong Kong— Anonymous
- I thought the lines in the sky left behind by airplanes were "sky scrapers". Makes sense.Anon
- I thought if I left the door open too long, a dog would come from the cupboard in the washroom and eat me
Anon - when i was little i thought every time i left the room my parents turned into aliensAnon