Two things have happened so far that scared me (I'm a coward so sorry if its boring).

It was 4 am, bored of questing but not wanting to sleep yet, I decided to hunt pets to get started in battling and I remembered about the very strong Anubisath Idol that was mentioned so often in reddit, googled to see how to get him, c'thun raid... I was already spoiled that he sent creepy whispers by another thread in reddit (two specifically: "you will die" and "your friends will betray you") so I was prepared. I was not, around 4 bosses in I was already scared shitless because being around 4:30 am the only sounds I heard were the instance sounds plus being alone in there made me feel unsafe (it was my first time running solo content, seeing some people beside me in dungeons and shit feels like a very different game), I kill the twins after being bounced around like crazy... no pet drop, I was dissapointed for a bit but I thought that since I was there already I had to finish the raid, still very inmersed because my headphones sound was very loud and armed by my newfound courage I took two steps out of the twins area and there I heard it, "Your heart will explode" and I feel a pat in my shoulder right after. It was my father telling me to go to sleep lol, I'm glad that my heart did not explode, in fact I might be very healthy, but the jumpscare was very memorable for me rofl.

The second thing that happened to me was that I was doing this quest http://www.wowhead.com/quest=29198/the-sanctuary-must-not-fall, finished it and headed to malfurion to turn in, for some reason I did a random 180 turn with my camera and there I see him, Lord Rhyolith swimming though the air heading straight at me, watching his massive model being closer and closer (by swimming) scared me so much, eventually he despawned before reaching me and I was left there looking at malfurion debating whether to turn in the quest or not. Also he had suposedly dealt with him too iirc in that very quest.