My friend verbally, and physically abuses his girlfriend?

Anonymous
One of my close friends has been with this chick for a couple years now. I visit them pretty often and I've noticed he likes to ridicule his girl a lot. Not in the sense of harmless poking fun but he will actually call her some really bad stuff and try to embarrass her. I've also seen him be physically abusive with her. He throws sh*t at her and will hit her with things. He'll also grab her and pull her around? I don't know how to explain the last one. He's just really rough with her. He doesn't do it in anger he does it because he thinks its funny. She'll ask him to stop but he doesn't let up. I've tried speaking up about it but he'll claim she likes it or that he's not hurting her. I've seen her cry because of things he's done.

I don't know how to approach this with them because its not my relationship so really its non of my business, but it really bothers me to watch him do this sh*t to her. Should I do something? Should I leave it alone? Should I talk to his girl about it? How would I talk to him about it?
My friend verbally, and physically abuses his girlfriend?
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