When someone is "stung to the quick", it means that they have been deeply hurt or offended. There are many synonyms for this phrase, including "cut to the core", "pierced to the heart", "wounded to the soul", and "crushed to the bone". All of these phrases describe the same feeling of emotional pain and vulnerability. It's important to be aware of the impact our words and actions can have on others, and to make an effort to treat others with compassion and respect. By doing so, we can help prevent others from being "stung to the quick".