I have two:
Thou shall not abuse your brother's game.
Man this one gets me. I have a brother that thinks he's playing for a million dollars or something. He shakes, slaps, bangs, curses, etc. Free play, man...free play. I re-install the tilt bobs when he's coming over, but that usually means he quits after 2 games.
No excessive text/phone detractions.
you missing your squeeze? stay with your squeeze. you're here to play pinball, dude