Elevator

Someone grabs me as I'm walking past:

"Can I take the service elevator?"

"No, sorry. That's for emergency use."

"But the wait for the regular elevator is so long."

"I'm sorry. Even doctors have to take the regular elevators. We can't tie up the service elevator with non-urgent needs."

"But I really want to get out of here."

"I'm sorry, I know. It's a pain, but you need to wait for the regular elevator."

He walks past. A couple of seconds later, I realize, turn around, and yell down the hall--

"Wait-- sir! You're a patient! You need to return to your room-- you haven't been discharged!"