1. At a play
  2. In a movie theater
  3. When someone is in the middle of a prayer
  4. The SAT's
  5. Yoga during shavasana
  6. At the OBGYN
  7. During swine flu while you're quarantined at an airport.
  8. During a TED talk.
  9. At a funeral
  10. During an informal job interview
    Suggested by @celine
  11. At a chamber music concert, during the slow movement of a string quartet
    Suggested by @molliekatzen