I have a short fuse 的意思是说某人脾气不好。fuse是导火线的意思，那么很短的导火线肯定是“一点就着”。
这样的人往往喜欢口头教训别人，口头教训别人的英文是 give someone a piece of one's mind, 或者tell someone off.
例如：
My boss has a short fuse and often tells us off /gives us a piece of his mind when we make minor mistakes......
我们老板脾气特别火爆，经常在我们犯错的时候数落我们。