My boyfriends brother is rude to me. And makes fun. How can I do the same to him?

So me and my bf have been dating for almost a year and his brother always makes fun of me. (In a mean way) it hurts my feelings and I tell my bf to stand up for me and he says he does, but when I ask him to tell me his bro says something he "forgets" sometimes. His brother is obsessed with this girl that won't date him, she's a whore and sleeps around with a different guy and I think it's stupid he's like that, so since he's been rude to me, what are some ways to be rude to him, to make fun of that girl he likes like he does to my bf about me. If someone's could please answer this. Cause I'm tired of this. Help please