Randomly looking around SO, I come across this question. What catches my eye is an unusual answer in that it's not worded at all:
Seems like a bug to me...may warrant looking into.
Meta Stack Exchange is a question and answer site for meta-discussion of the Stack Exchange family of Q&A websites. It only takes a minute to sign up.Sign up to join this community
It's just a bunch of empty characters:
Likely he posted an answer, realized it was wrong or otherwise, and removed all the content within the 5 minute grace period rather than deleting it, which he should have done. He might have thought he was going to update it with a different answer later, and maybe forgot. Happens more often than you might think (not the leaving it there empty part, though).