: Bart, I'd like you to read this copy of Johnny Tremain
. It's a book I read as a girl.
Bart: A book!? Pfffft.
Marge: I think you might like this. It's about a boy who goes to war; his hand is deformed in an accident.
: Deformed? Why didn't you say so! They should call this book Johnny Deformed
So, there's this book, or movie, you've heard about many times, so many times in fact, you feel you know the whole plot, even though you've never actually read it/seen it. Then you find out about this twist that no one who told you about it ever mentioned
, which ends up making the story sound ten times
Essentially, this trope is the polar opposite of It Was His Sled
; a famous story with an interesting twist to it that almost nobody knows about.