... he therefore vigorously strode to the apt door, turned the knob
and pulled on the release bolt.
The door refused to open. It said, "Five cents, please."
He searched his pockets. No more coins; nothing. "I'll pay you
tomorrow," he told the door. Again he tried the knob. Again it
remained locked tight. "What I pay you," he informed it, "is in the
nature of a gratuity; I don't
have to pay you."
"I think otherwise," the door said. "Look in the purchase contract
you signed when you bought this conapt."
In his desk drawer he found the contract; since signing it he had
found it necessary to refer to the document many times. Sure enough;
payment to his door for opening and shutting constituted a mandatory
fee. Not a tip.
"You discover I'm right," the door said. It sounded smug.
From the drawer beside the sink Joe Chip got a stainless steel knife;
with it he began systematically to unscrew the bolt assembly of his
apt's money-gulping door.
"I'll sue you," the door said as the first screw fell out.
Joe Chip said, "I've never been sued by a door. But I guess I can
live through it."
-- Philip K. Dick. Ubik (novel, 1969) page 24-25.