"Adding Insult to Injury" joke

Two sisters came home from school crying their hearts out.

"What's wrong with you both? asked the mother.

The first sister started wailing. All the kids at school ever do is make fun of my big feet."

"There, there," soothed the mother. "Your feet aren't that big." She turned her attention to the second sister. "Now why are you crying?"

"Because I've been invited to a ski party," weeped the second sister, "and I can't find my skis."

"That's okay, said the mother, "you can borrow your sister's shoes."