keep one's shirt on不要简单地理解为“穿好衬衣”，实际意思是“耐心点；冷静点；别生气”。

【例句】
He is only a child, so if you want to teach him something, you should keep your shirt on.
他只是个孩子，所以如果你想教他东西，你要耐心点。

I know you're excited, but keep your shirt on and wait for the surprise.
我知道你很兴奋，但保持冷静，等待惊喜。