"Kept one shirt on" is a phrase used to describe someone who remains composed and maintains their cool in a difficult or tense situation. Some synonyms for this phrase include "maintained composure," "stayed calm and collected," "remained composed," "kept a level head," "stayed unruffled," and "retained one's poise." These phrases all convey the idea of managing one's emotions and not allowing external pressures to affect one's demeanor. Keeping one shirt on is important in situations where it is necessary to be professional, level-headed, and in control, such as in a business meeting, presentation, or high-stress environment.