a pain in the ass第一眼一看还会以为是“屁股疼”的意思，其实正确意思是“讨厌鬼，烦心事”，跟这个意思一样的短语还有“a pain in the neck”。

【例句】
In scientific terms, teenagers can be a pain in the ass. But they are quite possibly the most fully, crucially adaptive human beings around.
从科学角度来看，青少年可能是个讨厌鬼，但他们很可能就是最出色最彻底的环境适应者。

Mowing the lawn in the morning is a pain in the ass. It's killing me!
一大早来修理草坪真的是太烦人了, 感觉要疯了。