Tv addicts use 1/2 the water of a gamer - dominant thumb only
  needs washing. Android and iPhone obsessers: wash only your
  dominant index finger, unless you're from the Middle East - you
  probably use your middle finger, as you don't have the same
  taboo we have in the US about it, and it IS the longest finger.
  Drivers: Wash both hands and feet, since they each get a
  workout. If you have road rage, you should wash your neck,
  because it gets a workout from twisting it around to yell at the
  idiot driving next to you. "