I used to hang out on the Wattpad forums for some reason. Actually there was a little sub-forum called The Pub that was a lot of fun and some very cool people that were totally not the usual Wattpad demographic (i.e. not 12 to 15 yr old girls posting One Direction sexual fantasies or Twilight fan fic, written mostly in text speak).
We had a real laugh for a while then I started getting cocky and fucking with the less intelligent members. It was like shooting fish in a barrel with a machine gun, but good fun to my ultimate shame. I've always been a horror writer, so I decided to start a story wherein I would transcribe the supposed events of a seance in which a creepy demon spirit is accidentally summoned. The story comments, however, would contain the true meat of the prank.
I actually made five ghost accounts (no pun intended) and put a lot of effort over a 6 month period into using them to post regular stories and collecting fans. I even invested effort in the profile details and would spend some time each day on each account making friends with people (mostly my already existing bunch of friends in the forums).
When the story was posted it was popular enough to have a large audience. In the comments my six accounts (5 ghost and my actual account) started posting details about spooky goings on occurring as they were reading the story. Things like light bulbs breaking simultaneously in their homes as they are talking to each other in comments, then black mists appearing on the ceiling, stuff like that. Things five apparently genuine people who live hundreds of miles apart couldn't possibly be experiencing at the same time.
Then the demon account appeared. I had a lot of fun with that one. She spoke Latin. Backwards. Her profile picture was a white blank which occassionally changed into some of the most horrific images I could find so that people who were visiting her profile page would see a creepy picture and announce it on forums only for everyone else to go look and see just a white blank. People really started to question their own sanity and freak out.
The fun really ramped up when the five ghost accounts were possessed, live on the forums, one by one. They each announced they were experiencing fucked up shit in their homes and were panicking, calling the cops etc. Then suddenly they'd start speaking Latin, backwards. Their profile picture would change into a white blank.
I can't emphasise how much this freaked some people out. I had a lot of apologising to do after because some of the people who lost it were actually good buddies I'd known for years on the forums and I did feel genuinely bad when they started spilling their guts in PMs and telling me just how badly I'd messed with their minds. People couldn't sleep. They'd missed days at work or school with worry for the people whose accounts had been possessed.
Meanwhile the demon account was gaining a ridiculous number of fans and endless PMs offering everything from sexual favours to souls in return for power, money etc. It confirmed what I had always suspected about the Wattpad demographic: that they're largely a bunch of deviant horny teenagers with zero ethics.
Unfortunately one of the people that really got messed up by the whole thing took a violent disliking to me and started stalking me. It was a high emotion prank and backfired in that respect. I had to dump my account and all my passwords. The crazy woman even hacked my Facebook.
Sorry I don't have a link to the story or anything like that. It was a long time ago and the accounts involved are all deleted.