My two favourite answers to the question regarding Order 66 and how the clones knew not to kill Anakin. Both from the TFN Forums, both made me giggle incessantly.

"See, watch the trailer, Sidious says every single Jedi is now an enemy of the Republic. Anakin's married, so he's safe."
-- Sith Magician, (thread)

"Anakin had a sign on his back that said 'Don't shoot me'."
-- TwilightTraveler, (thread)

LOL. I'm never gonna be able to hear that line or watch the marching-on-the-Temple scene without thinking of those now...

(comment on this @ livejournal)