When Marge gets mugged, she becomes agoraphobic and can't leave the safety of her home. She holes up in the basement and starts working out on a weight set.

She gets stronger and stronger, enough so that she's able to re-enter the world and beat up the man who robbed her, but she takes it too far and becomes a steroid-crazed bully as she beefs up for the "Iron Maiden Fitness Pageant."

When Homer appeals to her to calm down, she finally relents and goes back to being the old Marge.