What are your thoughts on the saggy boob "jokes"?

I don’t see the humor in it. And where did this come from? Is this all we have left to make fun of, old women with sagging boobs and ditzy blond girls, because everything else has become Politically Incorrect and Offensive? Blond jokes are fine. If they’re good I’ll pass them on. But this saggy boob trend…can someone explain where the humor is in it?