I used to believe that those vans you see with the ladder on the back that leads up to the roof actually went up to a pool that was on top of the van.
A childhood belief about swimming pools

others believed things like this
- I believed that the ladder on the back of a trailer/rv led up to a swimming pool.— marilese
- I believed travel trailers had a pool on top because the curved ladder was the same.Anon
- I used to think that Christ the royal master leaned against the throne. rather than leads against the foe.Anon
- I used to think that a carpool was one of those bug, long limosine's with a pool all the way in the back.— Annie
- I believed that the Kreepy Crawlie used to clean our pool, would follow me around the pool and eat me. — Mother-of-2
- My mother told me that ice cream vans were ambulances for little children.— Buzz