Well, if you want the end of joke….
The elevators doors open but slam shut too fast to exit, crushing anything that happens to be in-between. The doctors watch the cycle a few times. The psychiatrist finally says " What the hell. I never actually touch my patients," and he sticks both of his hands into the malfunctioning door, losing both his hands but allowing him to exit the elevator. The radiologist sees this, looks at his hands, then has an idea: “I sit all day in a dark room. I don’t need to stand.” So he jams both his feet into the door, amputating both his feet, but escaping the elevator. This just leaves the surgeon. The surgeon looks at his hands, then he looks at his feet----and shoves his head between the doors.
(And yes, a surgeon told me this joke.)