I think when you're riding on DA BUS similiar sort of Etiquette should be shown as if you were at the library. As Ms. Crabtree would say "SIT DOWN AND SHUT UP!"
This also applies to pricks who have too loud conversations on their phones. Not everyone wants to hear your story about how you nailed that bird at that party at the top of your lungs.
In these situations the bus conductor has my permission to throw your inconsiderate ass from the moving bus into incoming traffic, while the other passengers, all laugh, point and take pictures.