Folie à Deux"? Joaquin Phoenix, Lady Gaga and director Todd Phillips break down the wild ending and Gaga's triumphant song.

Somebody who was out of touch with the world, laughing at school at something horrible that has happened. How to explain that to the principal?" In Joker, Fleck's outbursts were triggered when he ...

his killer begins laughing uncontrollably. Then, just out of focus in the background, we see him carve a smile into his face, an unmistakable nod to The Dark Knight's Joker's scars. Oh ...