Smashing down the middle in badminton doubles — why it works (the 'whose ball is it?' moment of confusion between two defenders), where exactly to aim (slightly off-centre toward one defender's backhand body), and when to use it (after a couple of corner smashes have spread them outward). Plus the three default conventions for who takes the middle on your side — forehand-side player, whoever isn't already committed, or the back player on lifts.