How can I stop my elder sister from mocking me all the time?

It sounds like you are getting a hard time. I have a brother and a sister. My brother has a very bad temper and double standards and purposely tries to wind me and my sister up. I stopped reacting a long time ago and because he gets no reaction, he very rarely tries anymore to annoy me. My sister, on the other hand gets all worked up and he loves her reaction so he does it even more. I have tried telling her to just not react but she can't help herself. I suggest you do not react in any way when she is being a *****. Not one bit. Only respond when she is treating you like a human being. It should work.