Temper is the one thing you can’t get rid of by losing it.

The line is a compact paradox built on the double meaning of “lose”: to misplace something versus to lose one’s temper. Nicholson’s quip suggests that anger is self-perpetuating—an outburst doesn’t eliminate the underlying disposition; it often reinforces it through habit, regret, or escalation. The joke also implies a moral lesson: self-control can’t be achieved by venting, because the act of “losing” temper is precisely what keeps it present in one’s life. As a piece of aphoristic humor, it fits a tradition of wry observations about character: the traits we most want to discard are rarely removed by indulging them.