Your mama is so ugly. Even if she threw a boomerang, it wouldn't come back!
I don't find that funny. Are you targeting my mother's looks because she's a woman?
It's just a joke, and I'm targeting your mother.
Although the target of the joke was my mother, I don't think he would make a joke like that about a man. Women have more value than just their looks, and insulting a woman because she is ugly places all of her value on her superficial qualities. Before you make a joke about a woman, ask yourself if he would make the same joke about a man.