Hmmm...if I'm being honest with myself (sorry, icky warning ahead), before my surgery in June the nurse ended up making a dire mistake with the IV. I was already panicking a lot and hyperventilating annnnd she tried again...it didn't work...I was bleeding. By the forth try she got it right but I almost fainted. Of course I ended up falling deathly ill for weeks the day after.

Oh and one time someone knew something I did by myself in my room (back then was pretty rare) despite there being no means of knowing it. Never spoke of it ever and then...the person who doesn't even live with me randomly asked one day "Why were you [insert what I did] last Friday?" rather accusingly and incredulously. It was terrifying and to this day it still bothers me a lot. :/