When I was little, I used to think that in wars the armies would fight by slapping each other with fake limbs (arms,legs). It makes sense, "army", "arm".
A childhood belief about wars

others believed things like this
- I thought the lines in the sky left behind by airplanes were "sky scrapers". Makes sense.Anon
- I used to believe that it was the Star Wars "Tri-ology" instead of the Stars Wars "trilogy".— keith Key
- I used to beleive that all pains were headaches. So for example, I had headaches in my stomach, legs and arms.— James
- I used to believe that the salvation army was an actual army.Anon
- I thought a major general is more powerful than just a general (which still kind of makes sense to me)— Demond
- I used to think that world wars's were called war wars. So then World War II became War War II.— Maria