Someone who is thin-skinned gets hurt or angry very easily when people criticise them, joke about them, or disagree with them. The picture is physical: your skin is your protection, and if it is thin, small things get through and sting. It is a criticism, though a fairly mild and everyday one — you are saying the person reacts more strongly than the situation deserves, that they cannot take normal, ordinary comment. Note who it usually gets said about: bosses, politicians, public figures, anyone whose job means being criticised. Saying a leader is thin-skinned is a common political insult in English-language news. It is nearly always used of people, not things, and it comes after the verb be or before a noun: he is thin-skinned, a thin-skinned manager. Its opposite, thick-skinned, is used just as often and is a compliment: able to take criticism without being wounded. One thing worth noticing — the word describes a pattern, how someone generally is, not a single moment. You would not normally say someone was thin-skinned about one particular remark; you would say they took it badly.