We need a pony. And the moon on a stick. By next Thursday.
Of course, we in the real world know that shaved apes like us never saw a system we didn’t want to game. So in the event that sarcasm detectors ever get a false positive rate of less than 99% (or a false negative rate of less than 1%) I predict that everybody will start deploying sarcasm as a standard conversational gambit on the internet. Trolling the secret service will become a competitive sport […] Al Qaida terrrrst training camps will hold tutorials on metonymy, aggressive irony, cynical detachment, and sarcasm as a camouflage tactic for suicide bombers. Post-modernist pranks will draw down the full might of law enforcement by mistake, while actual death threats go encoded as LOLCat macros. Any attempt to algorithmically detect sarcasm will fail because sarcasm is self-referential and the awareness that a sarcasm detector may be in use will change the intent behind the message.
http://www.antipope.org/charlie/blog-static/2014/06/we-need-a-pony-and-the-moon-on.html#more