lose your cool
US /luːz jʊər kuːl/
UK /luːz jʊər kuːl/

1.
perder a calma, ficar irritado
to suddenly become angry or upset
:
•
He tends to lose his cool when things don't go his way.
Ele tende a perder a calma quando as coisas não saem do jeito dele.
•
Even under pressure, she rarely loses her cool.
Mesmo sob pressão, ela raramente perde a calma.