Nearly halfway through his latest special, Ridiculous, Louis C.K. asks his audience to help out with a joke. When he announces “I’m so old!,” the crowd is meant to respond in unison, “How old are you?” Another comedian might answer with an exaggerated zinger. Instead, C.K. deadpans a series of grim realities about aging that are funny by way of being uncomfortably candid. How old is C.K.? “I am so old that I live in the present for the first time,” he answers, “not from wisdom or courage but fro