Our happy hour fact to amaze your drinking buddies with.

The mood on Twitter predicts what's going to happen in the stock market with 87 percent accuracy.

Researchers from Indiana University analyzed the tweets of 2.7 million Twitter users in 2008, dividing them into six categories of emotions. They were surprised to find that the higher percentage of "calm" tweets on a given day, the higher the Dow Jones Industrial Average was in the following two to six days. In fact, this method yielded a 87.6 percent rate of accuracy.

"I sank into my chair. That's a pretty big result," associate professor of informatics Johan Bollen told Wired about his discovery. "It was one of those 'Eureka' moments."

It was one of those "Eureka" moments Bollen probably should have kept to himself. (And then profited from.)