Looking back I realise that some things that were completely normal for us growing up, actually could have been pretty dangerous had anything gone wrong.
In primary school my best friend's family had a van, and we would often ride in the back of the van unrestrained to go to events including a few hours away.
We thought it was hilarious being tossed around on corners and sleeping in the back on long journeys. Had there been an accident we would have been projectiles and likely forcefully slammed up against the metal partition between us and the front seat.

How about you? What things were totally normal for you as a child that were actually potentially problematic?