"Lost one's pink" is a phrase that's not used very commonly in modern English. It was used more frequently in the past to describe someone who had lost their composure or was acting irrationally. Some synonyms for "lose one's pink" could include "losing it", "snapping", "losing one's cool", "freaking out", or "losing one's temper." These phrases all describe a state of emotional turmoil or distress, usually when someone becomes overwhelmed with a situation or is unable to cope with their emotions. While "lose one's pink" may no longer be in common usage, its synonyms still convey a sense of losing control and emotional upheaval.