You might have a hard time defining "irony," but children as young as four get it. Researchers for a new study observed the homes of 39 two-child families and found that all but one of the children understood at least one ironic comment their parents made, and some even used irony themselves. Hyperbole, specifically, is a form of irony 4-year-olds seemed to have no trouble with; they got better with other kinds of irony by age 6, the Telegraph reports. (More irony stories.)