What is the origin of the idiom "mutton dressed as lamb" and when to use it?

The origin can be traced back to the literal meaning of the words "mutton" and "lamb." "Mutton" refers to the meat of an adult sheep, while "lamb" refers to the meat of a young sheep. When used as an idiom, "mutton dressed as lamb" is typically used to describe an older person who is dressed or styled in a way that is more appropriate for a much younger person, usually in a manner that is trying to appear more youthful or attractive than their age would naturally suggest. It is often used in a critical or disapproving manner to comment on someone's clothing, appearance, or behavior, suggesting that they are trying to deceive or misrepresent themselves by pretending to be younger than they actually are. The idiom is commonly used in informal or colloquial contexts, often in discussions related to fashion, personal style, or age-related matters.