I think the previous answers are not really correct, sorry. I used to watch this programme a long time ago, Sophia is very blunt and often insults the others. When Dorothy says 'everything just hangs on me', Sophia's reply is intended to mean that as Dorothy is older, Dorothy is physically sagging (eg drooping breasts etc.) and that's why Dorothy has to cover up. It's an insult concealed within a double meaning, which is why they insert the loud canned laughter. Similarly, in the second example, when Blanche realised that her dress is not unique as promised by Mr Marty, she is angry and her reply that "Mr Marty's going to be left with one of a kind" is a threat of physical violence, implying she would like to give him a black eye for example. She obviously will not go and hit Mr Marty really, the line is intended to show she is angry and would like to hit him. Again the humour is based on a double meaning. I think this type of humour, which is very context driven rather than relying on the meaning of the actual words, must be very difficult for an English learner!

Sharon is 100% correct. I hesitated to explain the joke, but I glad she did it and did it well.

It means Blanches dress not fit well it is very loose. it looks like it is still hanging up in a clothes store rail/hanger. I do not know the sitcom, but I feel that maybe blanche wears a small size bra. or is extremely thin or skinny. Mr Marty did not sell two one of a kind originals because both girls/women have the same dress. Therefore implying that there must be one original left at the store. You will have to wait until people who know the sitcom give answers.

The Golden Girls series has many sexual jokes. You won't hear these sexual jokes in real life and won't read them in books.

Hi Irene, “hangs” and “on” in this case are not together, that is, not a phrasal verb. The dress hangs (you know, like we hang our dresses on a hanger in the closet?) Which means that she does not have curved to make the dress look shapely. It just hangs “on her”.