"Potty training is a nightmare." So begins advice from Meghan Leahy, advice columnist for The Washington Post. More accurately, potty training has, of late, BECOME a nightmare, thanks to advice of the sort Ms. Leahy dishes. Her approach? Do nothing. The child will eventually use the potty on his own. That may be true, but what Leahy fails to add is "after the child's mother has had a nervous breakdown."