I will give you the answer on this one right now: It’s kidney stones! Usually requiring the use of opioids to alleviate it, it is perceived as the most painful experience by both men and women who get through it. However, this introduces another interesting question: Is it more painful to get hit in the balls or giving childbirth?
As it turns out, the answer is a little more complicated than you might think. ASAP Sicence has an interesting video on this: