The next time you're in line at Starbucks, take a closer look at the people ahead of you. You may think you're safe, but if you notice any coffee-orderers not requesting room for milk, it's time to run. Yep, forget your seasonal beverage order, and run. Because that innocent-looking lady on her bluetooth just ordered her coffee black, and guess what? That makes her a psychopath — if recent research from Innsbruck University in Austria is to be taken seriously.In a study of nearly 1,000 people, researchers found that those who preferred bitter drinks and foods were more likely to exhibit more "malevolent" characteristics, including "Machiavellianism, psychopathy, narcissism, and everyday sadism." It's like Mom always said: Steer clear of those everyday sadists.In addition to black coffee, radishes, celery, and tonic water were also used to gauge participants' psychotic tendencies. From the looks of things, although this was not noted in the study, rabbits must be the biggest psychos of the animal kingdom.The study cited intense eye contact as another marker of psychopathy. So the next time you see someone locking eyes for too long with the barista, listen for that person's coffee order, try to make him or her yawn , and then, maybe call for help.