在英语口语中，固定搭配 “as sick as a dog” 通常用来形容一个人因为吃坏了肚子而在一段时间内 “身体很不舒服，病得很严重”。在描述吃坏肚子的上下文中，“as sick as a dog” 也可以指一个人 “呕吐得很厉害”。它可以和动词 “be” 或 “feel” 搭配使用，即 “to be as sick as a dog” 和 “to feel as sick as a dog”。

例句
I’m going to have to get off the train as I feel as sick as a dog.
我得下火车，因为我恶心想吐，难受得要命。

Doctor, I was as sick as a dog after eating a pineapple. I vomited a lot.
大夫，我吃了一个菠萝之后，难受得不得了，吐得一塌糊涂。

He couldn’t come to work yesterday because he was as sick as a dog. He ate too much the night before and felt really ill.
他昨天不能来上班，因为他病得很严重。前一天晚上他吃得太多了，感觉非常不舒服。