Don’t use this! It is really very rude to call anyone a “bag”. It’s mostly used as “old bag” and it’s derogatory. I think the only situation where it might be taken as funny rather than derogatory is in a comedy or a stand-up show. Even then, tread very carefully.

Generally speaking, when you use "bag" or "old bag" while referring to someone, it would be considered rude. You could say it's slang and it could also be used in a joking manner. Whether it's an insult or whether it's just funny, of course, depends on context.

Both are very correct. The term is offensive. However, there is an old humor to the phrase that was a staple in vaudeville, and sketches from the 1930’s. The scene is usually at a travel location where two women place their suitcases on the ground for handling. Two employees appear. One says “help me with these bags.” The other says “ok, you take the tall one and I’ll take the short one;” or, “ok, you take the bags and I’ll get the suitcases.” The old joke was using the terms bag and suitcase interchangeably when the use of the word “bag” was then a slang term for a woman. But, it is now considered derogatory and you won’t hear it except in old movies. BTW, English has several old terms that started in vaudeville; some are still used and some have been abandoned.

Well I just found out that I got called "Bag" yesterday. So I went to search it up to see what it means. So thank you