Why do people talk about the The Trousers of Time when the daft bugger never actually wears them? No-one wears them, you simply fall continually into the waistband, not knowing from which leg you'll come out of.
In one universe, Rincewind, the Discworld's worst Wizard, chose not to speak the words of the Spell in his mind and found himself falling down one leg, which would lead to him going on many adventures quite against his will.
What would've happened if he'd fallen down the other leg?