Rule 5 of the Etiquette Code is simple: do not be a Blerch.
A Blerch is a person who consistently offends others with their inconsiderate actions, much like a fungus infects a otherwise healthy plant.
If you are a Blerch, there is hope for you. You can change your ways, but first you must read Rule 6.
Or, you can read Rule 7 if you're feeling particularly Blerch-y.
Or, you can read Rule 8 and learn about the importance of proper Blerch-repellent sprays.