不好意思。

You can use it as a standalone phrase or at the start of a sentence. Want to squeeze past someone on the subway? Say Bù hǎoyìsi. Late to a lunch date by five minutes? Say Bù hǎoyìsi. It functions as 'excuse me,' 'sorry,' and 'I feel a bit shy' all at once. You will hear people say it with a slight nod of the head.

Use it when you need to interrupt someone. It works perfectly when you are asking for directions. Use it when you receive a compliment and feel a bit bashful. It is great for small favors, like asking a waiter for more napkins. If you accidentally bump into someone's shoulder, this is your go-to phrase. It keeps the social gears grinding smoothly without making things too serious.

Do not use this for major mistakes. If you crash someone's car, Bù hǎoyìsi will sound incredibly rude and dismissive. In those cases, you need the heavy-duty Duìbùqǐ. Also, do not use it in very high-stakes legal or life-or-death situations. It is too casual for a courtroom. It is for the 'oops' moments of life, not the 'oh no' disasters.

Chinese culture places a high value on 'face' and social harmony. Bù hǎoyìsi is a tool to preserve that harmony. It shows you are aware of the other person's space or time. It actually stems from a sense of 'inner shame' or 'modesty.' By saying it, you are showing that you are a considerate person. In places like Taiwan, you will hear it used almost like punctuation—it is that common!

You can add Zhēn at the front to make it Zhēn bù hǎoyìsi. This means 'Really sorry' and adds a layer of sincerity. If you are texting, you might see people use emojis like a blushing face after it. Sometimes people repeat it twice: Bù hǎoyìsi, bù hǎoyìsi to show extra politeness while rushing through a crowd. It is the sound of a polite society in motion.