packed/squashed like sardines idiom
拥挤不堪，（像沙丁鱼一样）紧紧挤在一起
If people are packed or squashed like sardines, they are positioned very close together so that they cannot move.
We were squashed like sardines in the rush-hour train. 我们像沙丁鱼一样挤在交通高峰时期的火车上。