Plutonium

Hello everyone,
As everyone know, The order of zombies Is 1) Dempsey, 2) Nikolai, 3)takeo, 4)richtofen
Me and my friends wants tò use a random character every time.
Is there any script already existing? or, if someone wants, to help me to write a script? I don't know anything how to write a script or a code
Thank you for everything!!