Imagine waking up on your birthday to
the usual barrage of well-wishes from family members and old
classmates on Facebook. Your friend has posted a mysterious
video, and when you click play, David Hasselhoff, (or Fran
Drescher, or Billy Dee Williams ) is there, singing happy
birthday to you, with a personalized message thanking you
for being such a huge fan. You might wonder how your friend
pulled off such a surprise.