Mormons: We’re thankful for the arm up our asses–what doesn’t kill us will make us stronger.
Reconstructionist Judaism: The arm up your ass isn’t really an arm at all, it’s something far more abstract and simple that reams everyone.
Roman Catholic: Father Flanagan, is that your arm up my ass?
OR
Roman Catholic: Whether you like it or not, having an arm up your ass is the way we’ve always done things, and the Pope says we should keep it up - but you might as well feel guilty about it.
I believe you would be required to pay for the arm up your ass, with the cost increasing as it is inserted farther during multiple sessions.
Hmph. That’s pretty much what they they do anyway.
Quakers: Be very, very quiet, and wave your arms in an odd fashion, to show your appreciation of the reaming that we all recieve.
Buddhism: With simple choices in life, you can set aside the pain caused by the arm lodged in your rectum.
Satanism: We gotta look after number one, so we’re only ever gonna fist our own asses…
Maoism: The revolutionary moves like an arm in the asses of the people.
Communism: We have our collective arms up our asses.
Mormons: Until the state of Utah formed, Mormon men were often allowed multiple arms in their asses. However, the rest of the United States made them change their laws, and they are currently only allowed one arm in their asses…
Og Worship: Dear Og, save us from the arms of ignorance implanted in the asses of the people!
The Imaginary Pink Unicorn: Please play leapfrog with me.
Confuscianism: Confuscius say, “Up the ass which is yours, is an arm, belonging to me”
Great thread. 
Internet Geek : All your ass are belong to us.
SDMB Troll: What is the third word that ends in “ass”?
Euty: ROTFLMAOPIMP!
Amish - no mechanical, new-fangled arms up our asses, please.
Buffy The Vampire Slayer fan: Can we shove more than one arm up Marti Noxon’s ass?
The Stoic: Although I feel the arm in my ass, how can I be certain it is there?
The Existential Nihilist: All is nothing, and don’t I look absurd with this arm in my ass.
The Positivist: I can sense an arm in my ass, an experience I associate with a loving, if rambuntious diety.