Angry friend asks for an order and boos at me

I was hanging out with my buddy, and he was getting bugged by his girlfriend. She was being a real pain in the ass, and he was losing his cool. I decided to step in and help him out. I asked her what she wanted, and she started yelling at me. She was so angry that I couldn't even hear myself think. I was like, dude, chill out! But she wouldn't listen. She kept on screaming at me, and my friend was just sitting there, feeling helpless. I had an idea. I told him to let me take care of his girlfriend. I knew I could handle her. I started talking to her in a calm voice, trying to reason with her. But it wasn't working. She just kept on yelling. That's when I decided to show her who was boss.