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!