1 loose cannon

松动的大炮（一触即发的脾气）

She is a loose cannon. = She is unpredictable and could cause trouble.

她喜怒无常，很能惹事。

例子：Don't argue with him after he drinks too many beers. He is a loose cannon when he is drunk.

他灌饱了啤酒时不要跟他争论。他喝醉了就像个松动的大炮。

1 six one way, half a dozen the other

一边六个，一边半打（半斤八两）

It is six one way, half a dozen the other. = It is basically equal.

两边基本一样。

例子：I think that if we go north and then east to get there or east and then north to get there it will be six one way, half a dozen the other.

去那个地方，无论先往北走，再折向东边，或者先往东走，再折向北边，都是一样的。

1 light a fire under your butt

在屁股下点一把火（促其行动）

I had to light a fire under his butt. = I had to give him a reason to motivate himself.

我得想办法让他行动起来。

例子：He graduated nine months age, but still hasn't found a job. I decided to light a fire under his butt so I told him that if he didn't find a job in one month, he would have to move out.

他毕业已经九个月了，还没有找到工作。我得想办法让他行动起来，所以我告诉他，要是一个月里还找不到工作，就得搬出去。