The dinner_guest - a Twitter account that looks like a murderer's - was first discovered by TechCrunch Europe and quickly picked up by other sources like The Inquisitr.

He began his "career" by posting about kidnapping a man, killing him (inadvertently) and trying to make a shrunken head.

Personally I'm convinced it's a play. Tasteless for sure, no question about that.
But it's interesting that it was picked up by "real" media within a couple of hours after the first Tweets. Also interesting that dinner_guest first seemed very new to Twitter and the viral web, but also picked up very fast. At least he knows that 80 followers don't make a viral campaign.

But let me note that within 10 minutes after that post his followers had doubled to 160.

I myself would not follow him, I watch the phenomenon here:
http://search.twitter.com/search?q=dinner_guest

As a funny sidenote: here are the results "dinner_guest" on Google Image Search...

Update: the dinner_guest revealed her experiment on November 27th:

http://blog.freshegg.com/created-psycho-twitter-dinnerguest_2482