Hospitals are pretty crazy places to be in, let alone work. Everybody who needs them is ill, there's almost always some kind of emergency to attend to, and on top of all that, they are one of the most common places for people to die. Needless to say, it takes a certain kind of individual to make the world of health their job. When you work in healthcare, not only do you have to deal with all the serious, life-saving matters, but you're also forced to handle all the boring bureaucracy and snarky office politics that come with almost any professional role.
It makes sense that just as much as those in any other sector, people in healthcare rely on a hearty dose of memes to get themselves through the working day. You can never predict what the average hospital shift is going to be like, and the humor reflects that.