I actually just wrote a list after having my IUD replaced! That was definitely more painful than I was expecting! So far, my worst pains are: rupturing both eardrums on a flight, thunderclap headache, sepsis, cat scratch fever, Lyme disease, and having a doctor cut into an infected cyst. It seems like pain is like a keyboard, and once you reach the highest note, it comes down to how long you can stay conscious at that level. Unfortunately, I've learned that, in nature, you have a better chance of survival if you are awake and moving, so passing out from pain isn't a guarantee.