sardine 沙丁鱼，be packed like sardines比喻十分拥挤，拥挤不堪，挤得水泄不通，人都挤成肉饼了。

【例句】
The bus isalways packed like sardinesat this time of day.
每天这个时候公交车总是挤满了人。

I'd better stay at home during the holiday. I don't wanna be packed like sardines.
放假我还是待在家里吧，我可不想被挤成狗。