a pain in the neck
不胜其烦，不堪其扰

释义：
pain in the neck - a bothersome annoying person; something or someone that causes trouble; a source of unhappiness;
让人烦扰或徒增负担的人或事
例句：
This new class is a pain in the neck. It's so difficult….and boring!

这门新的课程真是够恼人的，不光很难，而且无趣！

The little children were a pain in the neck on the long car trip, because they wouldn't be quiet.

小孩子们在长途旅行中总是很烦人，怎么也安静不下来。
French leave

悄悄离去，不辞而别。

这个说法来自于18世纪法国风俗，意为不通知主人而自己离开。

Usage Note: In the 18th century in France, it was the custom to leave an official event or party without saying goodbye to the person who had invited you.

例句：Is Ray really ill again, or is he just taking French leave?
Ray是真的生病了还是不辞而别了。