羞愧

Use it as an adjective or a verb. You can say someone 'feels' 羞愧. Or you can say an action 'makes' them feel that way. It often follows words like 感到 (to feel) or 十分 (very). It is a heavy word. Don't use it for small things like tripping over a rug. Use it when your conscience is actually bothering you.

Use it when you've genuinely messed up. Maybe you forgot a best friend's wedding. Perhaps you lied to your boss and got caught. It works well in apologies. It shows you understand the gravity of your mistake. It is common in literature and heartfelt conversations. If you are writing a sincere apology letter, this is your go-to word.

Avoid it for minor social awkwardness. If you have spinach in your teeth, use 尴尬 (awkward) instead. 羞愧 is too heavy for that. Don't use it when you are the victim. If someone insults you, you aren't 羞愧, you are 生气 (angry). It is strictly for your own perceived moral or social failures. Using it for small things makes you sound overly dramatic.

Chinese culture places high value on 'face' and social harmony. 羞愧 is the emotional guardian of these values. Historically, it was linked to one's duty to family and society. Feeling 羞愧 shows you have a 'sense of shame.' In many Eastern philosophies, having a sense of shame is a sign of a good character. It means you are capable of self-reflection.

羞愧难当 is a great four-character idiom. It means the shame is so strong you can't bear it. You might also hear 惭愧. That one is slightly lighter and more common in daily speech. 羞愧 remains the more intense, literary choice. Use 羞愧万分 if you really, really need to emphasize how bad you feel.