Wiktionary
lose my cool
vb. 1 (alternative form of lose one's cool English) 2 (en-third-person singularlose my cool)
Usage examples of "lose my cool".
The truth is, I totally lose my cool in an emergency, and if things turn out okay, it's through no effort of mine.
Yet it seemed nowadays I only had to hear my wife's name and I would lose my cool.
He might as well be wearing a chartreuse neon sign that says I AM ABOUT TO LOSE MY COOL, BIG-TIME.