What is one thing you would uninvent?

Just a question I heard yesterday... my first thought... leggings/stretch pants. But, then, I thought... it would've been nice if the whole concept of calories was different (like a plateful of salad would have the same amount of calories as a bowl full of ice cream). But, then again, I suppose man never invented calories or how they work, so maybe I should go back to the leggings. Leave a comment and tell me what you would uninvent.