I used to think that the London Bridge song went "London's britches falling down" I always felt really bad for people named London who happened to be shopping or something whenever people sang that song.
A childhood belief about misheard lyrics

others believed things like this
- Did anybody besides me believe that Londonderry Air was actually London Derriere?— Texas granny
- up until about 6 years ago i thought everton was in london!Anon
- When i was little i thought casualty was a big hospital in londonAnon
- When I was little I thought the london underground was a terrorist organisationAnon
- I used to believe that london, paris, venice, and switzerland were all cities in France. — an american...
- My mum told my older brother that dogs weren't allowed in London.— Fiz