lose your cool

lose (one's) cool

To lose control of one's composure, temper, or nerve in a given situation. He really lost his cool when the waiter dropped his food. I really lost my cool during the interview.
See also: cool, lose

lose your cool

COMMON If you lose your cool, you suddenly get angry and behave in a bad-tempered or uncontrolled way. At this point, I lost my cool and shouted `for goodness sake, stop!' `Why don't you sit down and have a drink?' — `I don't want a drink,' Anne replied, losing her cool.
See also: cool, lose