It can be fun to join in the water cooler talk and blame every little thing that goes wrong today on the fact that it’s Friday the 13th. But here’s a great luck secret: don’t say anything.

When everything is going your way, you’re socially attractive. People want to hang out with you. You’ve got “it,” and are in a key position to key lots of opportunities.

On the other hand, being the victim of bad luck is also contagious. Just mentioning the words “bad luck” can do some damage to the perception that other people have of you. It sounds irrational, yes, but welcome to the world of dealing with people.

Kristina Olson, an assistant professor of psychology at Yale University, studied the social effects of good luck and bad luck. As it turns out, we’re unbelievably to the “just world” hypothesis, a bias that makes us believe that good things happen to good people, and bad things happen to bad people.

Even if the layoffs at your company were done at random, the “just world” hypothesis makes us believe that the people left standing deserve it more. Did you get your report stuck in the copier? Maybe it was a technical matter beyond your control, but subconsciously we’re prone to believing that you’re technically inept and (gulp!) deserved it in some way.

Playing the lovable underdog who believes in bad luck—and then points it out—actually backfires, since we’re subconsciously prone to believe that people bring on their own bad fortune.

In Olson’s study, her subjects liked lucky characters (who found five dollars on the ground) almost as much as they liked people who did good, intentional acts. Even friends of the unlucky were affected.

Think it’s just because of a lifetime of social conditioning? Think again: her subjects were five years old. “Children are just as irrational as adults,” says Olson.