http://weknowmemes.com/2013/12/scary-stories-in-two-sentences-or-less/
some good ones here.
more: http://www.google.com/search?q=Scary+Stories+In+Two+Sentences+Or+Less
http://www.reddit.com/r/AskReddit/comments/1u2en6/can_you_write_a_scary_story_that_is_written_in/
http://www.reddit.com/r/AskReddit/comments/1iwylh/
http://thoughtcatalog.com/michael-koh/2013/07/40-freaking-creepy-ass-two-sentence-stories/
( ^ "You wake up. She doesn't." totally makes me think of an amazing Breaking Bad moment.)
Thses are really good, I've encountered some of them before
Great stuff!