You literally don't know what you're getting into sometimes. I had an essentially harmless cyst in my wrist, the doctor suggested draining it with a needle on

You literally don't know what you're getting into sometimes. I had an essentially harmless cyst in my wrist, the doctor suggested draining it with a needle on the spot. "Sure, how bad can it be?" I'm completely unbothered by needles, always figured my pain tolerance was decent and they did local anesthesia anyway. Turns out that it was a big needle and the anesthesia basically didn't work: the instant the needle punctured my skin, I felt like I had been body slammed and a wave of nausea washed over me. I'd always figured people fainted because they were somehow scared of needles, but this hit me so hard that I could feel the room start to spin and my vision dim, and I had to lie down for a while. I was fine within minutes, but with something like shoulder surgery, a similarly casual decision could easily lead to weeks of agony.