For this kind of younger brother, first of all, you should set up a good psychological defense line, make yourself harder and let him say hurtful things, so that you won't be hurt. Then, we will fight back. First, educate your younger brother seriously and show your sister's majesty. If you don't listen, give him the cold shoulder and ignore him. Let him know that you have a bottom line. If his attitude doesn't improve at all, you really don't have to worry about this smelly brother. Live a good life and don't let him bully you again.