The words Polter and Geist seem to be of German origin:
"Polter" = to make knocking sounds
"Geist" = German for "ghost"
Louis: Not really Ryan, I just banished a poltergeist
Jim: You might not want to go in there for a while boys, I just left a hideous poltergeist!
Kell: Fuck me my arm aches, was in there half an hour dealing with a poltergeist!