My mom got mad at me because....?

I answered the front door wearing boxers. 2 of my moms friends that are girls came over and they rang the doorbell and my mom was in the shower and my sister is too lazy to wake up to get the door. I had been asleep but was awakened by the doorbell. So i just got up and answered the door and left to my room. My mom just came in my room and said why did you answer the door in your boxers? I said whats the problem? Its my house i can wear or not wear whatever i want. She said no you cant. And i just took off my boxers in front of her and said yes i can. And she got mad at me so now she's not letting me go to the movies tomorrow with my friends. I mean its my house what was wrong with that? I feel like just walking around the house naked in front of her friends just to give her something to actually get mad about. Who's right here my mom or i? Its my house right?