cool是冷，cucumber是黄瓜，as cool as a cucumber可不是像黄瓜一样冷，而是美国人经常使用的一个习惯用语，意思是指：当一个人碰到困难和麻烦时很冷静、很放松；镇定自若；泰然自若；沉着；十分冷静。

【例句】
Jeremy looks as cool as a cucumber on any occasion.
在任何场合杰里米都看起来镇定自若。

I am as cool as a cucumber when I walk in the dark forest.
当我走在黑暗的森林里时我相当地淡定。