zombies and potatoes

Everyone in the group closes their eyes. The game master then selects one zombie from the group by lightly touching his/her shoulder (noone from the group has to notice that). All the other players will be "potatoes". The master then gives the signal and everyone has to start walking around the room. When two people meet, they have to quietly whisper their roles to each other. If a potatoe meets another potatoe - nothing happens and they just walk away. But if a potatoe meets the zombie - it dies! In 5-7 seconds after it hears a person whisper "zombie" to his/her ear, the potatoe must scream and fall to the ground. Then he/she can open the eyes and watch the rest of the potatoes slowly killed by the zombie :)  

Another version of this game is Vampires. Potatoes present themselves as mentioned above and the vampires are always silent. When a potatoe meets a vampire it becomes a vampire. But when two vampires meet - the both become potatoes! Magic!