"adult" might be a bit of a stretch
  1. Automatic car washes
    So much fun!
  2. String cheese
  3. Building Lego sculptures
  4. Giant cardboard boxes that double as toys/houses/caves/anything
  5. Shooting trash into the trashcan from afar
  6. Blowing daffodils
    Why do people stop doing this as they get older? I could do this forever