You're running late for work and the only clean clothes you have that are office-appropriate have been lying on your bedroom floor in a heap for a week. You put them on and go look in the mirror, where you realize they're a wrinkly mess. That'll never do! You plug in the iron so it can heat up while you finish making breakfast. Once bolstered by a bagel, you head back over to the iron and get ready to smooth out the wrinkles quick.
Even if your boss is the world's biggest stickler about punctuality, you'd probably never decide to save a few moments by ironing your clothes without taking them off first. But the product warning on the side of the iron suggests otherwise. "Never iron clothes while they are being worn."