It's James Gordon's birthday, and the major crimes unit takes him out for drinks to celebrate, though he promises to see his daughter Barbara afterwards (she's baked him a cake). They give him gifts, some more appropriate than others, and then he hands them each something too: a handcuff key. Partly because such things are always going missing and partly because they symbolise the authority of the police. He explains this to the cops as Batman goes about his normal business.