I think I will call a friend of mine "whipped".
That seems mean. Why do you want to call your friend "whipped"?
Because his girlfriend has him wrapped around her finger.
I know you feel like your friend's girlfriend is too controlling of him but calling him whipped is not appropriate. You friend may be in love and wants to do things that please her. You should stay out of their relationship and not criticize him for his behavior.
Whatever, that whole relationship is the reason why our friendship is on the rocks. It's time for me to sit back and watch them fall apart so I can get my friend back.
It might backfire on you to call him names and criticize his relationship. He might get so angry that you are getting in the middle of his relationship that he might want nothing to do with you anymore.