One important aspect of the training that CCK's bodyguards underwent was learning to keep their lips sealed. For safety, one had to be like a ball, that is, completely sealed. Not even one opening was permissible.
身為經國先生侍衛，很重要的一個訓練是「守口如球」﹘﹘也就是安全要像「球」一樣，全密封起來，一點缺口都不能有。