It is even funnier with 3 in cloth - I just say something along the lines of 'I'm not spending $50 a week on nappies and I NEVER run out. Sometimes it is more of a nightmare to go to the shops with 3, so I have made it easier for myself by making sure that if I am low on nappies I only need to go to the laundry.' That usually shuts them up, considering co-ordinating nap times and the every day is hard enough without having to go and do an emergency supermarket trip.