Explaining on Instagram: "In The Dark Knight, one of the Joker’s most chilling moments was never written into the script. During Commissioner Gordon’s promotion scene, Heath Ledger suddenly began slowly clapping from his jail cell, locking eyes with the room and breaking the tension in a way no one expected. 👏😳 The reaction was completely improvised. Ledger sensed the moment needed something unsettling and decided to fill the silence himself. Director Christopher Nolan kept the cameras rolling