1. Weird or mismatched clothes. “Often aliens don’t fully understand the different styles, so they wear combinations that are in bad taste, such as checked pants with a striped shirt or a tuxedo jacket with blue jeans or sneakers,” noted Brad Steiger, a renowned UFO investigator and author.
2. Strange diet or unusual eating habits. Aliens might eat french fries with a spoon or gobble down large amounts of pills, the experts say.
3. Bizarre sense of humor. Aliens who don’t understand earthly humor may laugh during a serious company training film or tell jokes that no one understands, said Steiger.
4. Takes frequent sick days. An alien mightneed extra time off to “rejuvenate its energy,” said Dr. Thomas Easton, a theoretical biologist and futurist.
5. Keeps a hand-written or online diary. “Aliens are constantly gathering information,” Steiger said.
6. Misuses everyday items. “An alien may use white-out to paint its nails,” said Steiger.
7. Constant questions about customs of co-workers. Aliens who are trying to learn about our Earth culture may ask questions that seem to be stupid, Dr. Easton said. “For example, a co-worker may ask why so many Americans picnic on the Fourth of July,” noted Steiger.
8. Secretive about personal life-style and home. “An alien won’t discuss domestic details or talk about what it does at night or on weekends,” said Steiger.
9. Frequently talks to himself. “A space alien may not be used to speaking as we do, so an alien may practice speaking when it thinks it’s alone,” Steiger noted.
10. Displays a change of mood or physical reaction when near high-tech hardware. “An alien may experience a mood change when a microwave is turned on,” said Steiger.

The experts pointed out that a co-worker would have to display most if not all of these traits before you can positively identify him or her as a space alien.