On the church newsletter were these instructions -

Hold this paper close to your nose and breath deeply. If the sheet turns green, you need to see a doctor. If it turns blue see your dentist. If it turns red see your bank manager. If it turns black, you need to check your will, so see your lawyer immediately. If, however, it does not change color then there is nothing wrong with you, and there is 'no' reason why you shouldn't be in church next week.