"I must have been in my 30s when I found out that the map of the London Underground does not follow the actual routes. " - well it was like when I realised religion was total bowlocks for me, as soon as I saw the map I knew it could not be how the routes are laid out. Done by Harry Beck originally.
Prepare yourself for another shock, barry1010 - circuit diagrams for car electrical systems, circuit boards, etc. don't show how the components are actually laid out. :-)
I had encountered circuit diagrams before seeing the London tube 'map', so with its 'neat' appearance I have always seen it as a diagram showing the connectivity and order of arrival at the stations, rather than an actual map.
when i was *not all that* young we lived near a cemetery. I asked my mum what it was and she said "it's where they bury people".
For a long time (longer than i should have) i hated walking through, because i was on the lookout for someone jumping out and trying to bury us.
Plenty for myself but my favourite one was when I was watching Would I Lie to You where people say something daft about themselves and the other team have to assess if it's true or not.
Tomasz Schafermaker - the weather man - said he was in his thirties before he realised that lambs were baby sheep. He was filming lambing on a farm and asked why it was called lambing. Everyone including him was helpless with laughter. What a sport !