Every year companies’ mobile phone plans incur thousands and thousands of dollars in charges for … well, some really dumb stuff.

Company-issued cell phones usually come with an explicit — or at the least an implied — warning about what kind of behavior is, and isn’t, acceptable. Yet employees routinely manage to rack up huge mobile charges through totally non-business-related activity.

Horoscope text message alerts, pop music ringtone downloads, video game apps — those small costs add up fast, putting companies way over budget and leaving mobility managers scratching their head. I mean, who uses the “SexyCougar” SMS service on a company phone, anyway?

A lot of people, it turns out. And the reasoning for doing so can be fairly complicated, too, say behavioral psychologists who study this sort of employee deviance.

Distorted Perspective

Company culture and corporate leadership both play important roles in how employees treat their company privileges, whether it’s charging dinner to the company credit card, playing hooky, or downloading Angry Birds on the work phone. But primarily, it’s an issue of perspective.

“We find that as the distance between an act and its consequences grow and are more fuzzy and require more steps, people find themselves able to commit more dishonesty,” says Dan Ariely, a noted behavioral economist and author of Predictably Irrational and The Honest Truth About Dishonesty.

That’s why it’s easy to swipe a box of pens from the office, even though the same person probably wouldn’t actually take $5 from the till. The pens, even if they’re worth $5, are a few steps removed from the money they cost.

“But with cheating, it’s not about people thinking very carefully about it, or deliberating the costs and benefits,” Ariely says. “It’s about rationalizing. If people took money directly from the company, they’d have a hard time rationalizing it. But when its in apps and downloads and ringtones, that’s easier.”

Celia Moore, a professor of organizational behavior at the London Business School, agreed.

“It’s very hard for individuals to consistently act in ways that they believe are unethical,” Moore says. “So they go to great lengths to distort or reframe the truth in their own mind … it’s no big deal, everybody does it, I’m not harming anyone. And those kinds of statements are evidence of moral disengagement.”

So it becomes pretty easy for lots of people to rationalize firing off a few extra texts — even if they add up to cost thousands of dollars a month in overages for the company.

Company Culture

Further, Moore says that workplace culture plays a big role in employees’ engagement, and how they rationalize their behavior. Offices where employees are used to taking slight advantage of their perks breed more employees taking more advantage.

“People become socialized very quickly into the norms of the environment they’re in,” she says. “Employees learn what’s normal, what’s tolerated by their peers, and they assume it’s normative. And it is. So the self-sanctioning that ought to be triggered becomes less salient. … That helps people re-construe the behavior as morally neutral.”

Moore says she is also working on research that shows that employees’ levels of disengagement are influenced by their superiors’ behavior. “The more ethical people’s supervisors are, the less disengagement,” Moore says. “So leadership matters.”

In other words, did the boss download a Taylor Swift ringtone? If so, then who’s to say I can’t, too?

Shades of Grey

Ultimately, most employee deviance — whether it takes the form of reckless spending on mobile phones, or fudging on the expense report, or calling in sick with the “24-hour bug” — doesn’t come from a place of nefariousness, but rather of misplaced or misconstrued context.

And while there is certainly evidence that disgruntled employees are willing to take what they believe they’re owed (particularly if they feel as though they aren’t getting it already), the more common situation is one where employees’ behavior strays into some grey area — not wrong, per se, but not strictly business-related, either.

“There’s the slippery slope,” says Ariely. “For instance, an app that could in principal be for work, but that is not necessarily; or something that could in principal be helpful. And after that first [download], the deterioration of that ‘slippery slope’ increases.”

And that’s how mobility managers end up finding SexyCougars charges on the monthly bill.

Related: BYOD Is Great, But It Doesn’t Make Data Any Cheaper.