A young woman buys a mirror at an antique shop, and hangs it on her bathroom door. One evening, while getting undressed, she playfully says "Mirror, mirror, on my door, make my bustline forty four".
Instantly, there is a brilliant flash of light, and her breasts grow to enormous proportions.
Excitedly, she runs to tell her husband what happened, and in minutes they both return. This time the husband crosses his fingers and says "Mirror mirror on the door, make my penis touch the floor!".
Again, there's a bright flash, and then his legs fall off!