Ahh yes i've heard many many many of these stories growing up. Strangely enough the same story by different people in different parts of the country that all happened to "their mothers friend" or "their sisters, grandmothers, daughters, friend".
My favourites include:
1) One brother bought a calendar from a Chinese store. He didn't know what the Chinese characters said but that night i lay paralised in bed. He was pinned down by a demon! - (Actually, in the medical world this is a common phenomenon known as "sleep paralysis" where part of your brain is still sleeping).
2) One brother bought a picture frame from a second hand shop. He put a photo in there and hung it on the wall. The next day the frame was on the floor with the picture no longer in the frame!
3) One sister was difellowshipped and all the time she was disfellowshipped she heard demons talking to her. She called an elder who flatly refused to have anything to do with it. She once even claimed to have been raped by a demon - (The fact that this sister is a paranoid schizophrenic isn't mentioned though). She's reinstated now and still attends meetings. Brings all kinds of weird shit to the hall like old broken dolls and clocks that dont work.
4) Lets not forget that one we've all heard all around the world about a woman that went on the ministry on her own, knocked on a rapist/murderers door and wasnt touched because the guy could see two big fellas next to her. Obviously angels. My favourite version of this was when an old man re-told it in my old congregation during the Watchtower discussion. He said "...he said he saw two big black men either side of her". Why he felt the need to mention their skin colour is beyond me.
Even when i was in, i used to say to JW's that believed this shit "if i were a demon, with all that power and knowledge i wouldnt be using it to open and close doors, put backward messages in music or hide in a second hand shirt - i would MESS YOU UP."
Needless to say, it didnt go down well.