Okay, this is something me and my brother started doing when we used to go every summer together. While in line (or anywhere for that matter) we would pick out people that looked like celebrities or famous people. It's pretty fun to do and always gets me laughing. It is even more funny when you see that person that looked like a celebrity (or whoever you happen to spot) later on in your trip numerous times! And then every time you see them, you say, "Look! There's ___ ____!"
Some of the many 'celebrities' I have seen at WDW are:
Sean Connery
Victor French
Alec Guinness
Japanese Elvis
Bill Clinton
Laurence Fishburne