From Grant Morrison's masterful Supergods :
At the heart of [Chris Nolan's] The Dark Knight was a reputation-assuring performance that seemed to burn and fizz off the screen; it was hard to recognize the face of handsome young Heath Ledger under the scars and smeared makeup of the Joker, but he owned the screen from the moment he first appeared and slammed a pencil through a man's head until his final dangling turn as the hanged man of the tarot, condemning Batman to an upside-down world of darkness and madness. [emphasis mine]
When I first read this, the only reaction I can describe is a trite one: my mind was blown.
Judge for yourself:
|Hung, you may note, by his ankle|
...also hung by his ankle. And the standard Tarot reading of "reversal" is right there in the movie.
These things are hidden in plain sight.
Or, possibly, I'm insane.