When I was a kid, I knew that a "dead end" was where the road ended before joining another road, but I thought that if you drove down to a dead end, you couldn't go back and you had to stay there until you died. Hence the term "dead end".
A childhood belief about road signs

others believed things like this
- I thought when a road sight said Dead End that someone had actually died there.Anon
- i always thought that a DEAD END sign
as where they put all the road kill.
— pav - I used to think that if you went to the end of a road marked "Dead End", somebody would try to kill you.— Spooky
- I used to believe that a street sign that read "Dead End" meant that there were dead people buried there.Anon
- when i was younger i thought that areoplanes drove dead people to heavenAnon
- I thought that when you died, you had 2 weeks to be dead then you would magically wake up again, but as a babyAnon