i thought that the phrase "jet lag" was actually "jet leg" until i was 17...
A childhood belief about aeroplanes

others believed things like this
- I thought the phrase "At one's disposal" meant you should dispose of the person or thing.— Geirskogul
- The phrase 'Recycled toilet paper' always worried me.Anon
- I used to believe all Italian women were named Mia because of the phrase "Mamma Mia!"Anon
- I used to believe that the phrase "Mamma Mia" referred to a girl named Mia.Anon
- I used to think that the phrase "It's a dog eat dog world'' was its a dogey dog world.— Gabral
- We had an antique lamp that I thought was hideous and for years I thought "Art Deco" was a synonym for ugly.Anon