Zombie flashmob

"Shawn of the Dead" is an excellent british zombie / romantic-comedy movie.
My fiancée and I were staying in London for a couple days last week and had some fun making zombie noises in the subway, like the characters in the movie. And we heard some other people too :-)
It made me think that having a greater number of people doing this could create a cool/scary effect.

Why not organize a flashmob were the participants would act like zombies?

London would be a great place to do this.
In order for tourists and other bystanders not to get too freaked out, it would have to only last for a short but well coordinated time. Using the Big Ben bells as a signal and simulating zombies for a minute could be pretty effective, I think.

Update (2005/08/01): San Francisco is getting its own zombie flashmob with a twist: zombies can convert bystanders, so the mob can replicate.

Yeah. A flashmob would be wicked cool!

Well... here's one. But it's happening tomorrow, so get your skates on. And your flesh off.

I can see bystanders shooting zombies now...."I thought it was real! You're supposed to shoot zombies, right?"