Hi Ayushia51, the very fact somebody uses humour to belittle someone is a mark of the person being insecure, and they themselves don't believe in themselves, now with respect to coping, it's important to be assertive if someone is saying something that affects you even if it's a joke, you can start with politely addressing it that:
A) you don't like this mode of expression
B) You get it that the other may not intend to hurt you, however since it's affecting you so kindly do not engage in such behavior.
If the nagging doesn't stops, you need to take assertive measures, if the person still doesn't backs off, then realise, the other person said certain words, but then those words did not reach you, they still remain the the concerned person's confined space, one is entitled to have an opinion so let them speak their piece of mind but you are still immune from their perspective, you do not have to absorb their projection of ideas, as you have a shield around you. This is the imagery I am drawing for you to visualise. That we need not soak everything our environment is throwing at us, but that doesn't mean you shouldn't take a stand. So do speak up first, cause that also makes a statement that I respect myself enough to not let anyone belittle or ridicule me. Once you do that, you yourself will feel better about the entire situation.
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Once you know their joke is being used as a medium to make you feel inferior about yourself you already have insight into why they are doing what they are doing.
You can clearly ask them to make better jokes which aren't disrespectful in nature. If they still continue with it then you have two options
1) Distancing yourself from them if that's not possible then second option might work-
2) Whenever they say something demeaning "jokingly" you can give a sarcastic reply like "wow you are so funny" or just play along and crack a similar joke on them to give them a taste of their own medicine because sometimes people need that. It will make them realise that you are not going to out up with the demeaning behaviour.