I believe this is a new one. If it already exists somewhere, please forgive me: I couldn't find it.
Like the title says - Walk Like a Zombie, but you're still alive. You could maybe press one of the function keys to start it. You could even make sounds and howl like a zombie. The idea is to lure unsuspecting players close to you. But then at the last second you pull a gun and BLAM, they're history. Hopefully. This is assuming they don't put 2 rounds in your head, of course.
Other zombies wouldn't attack you, naturally, as this would spoil the ruse. This also would make a great, ultra-slow method of retreating from zombie hoards.
-Scott