No matter how many times I hear about this, it’s something I just don’t get: Why do some big-time executives need to lie about academic degrees they never earned?

This topic is in the news again now that The Wall Street Journal has found that the chairman and CEO of gaming giant MGM Mirage has been lying about earning an MBA in finance from the University of Southern California.

According to the Journal, “J. Terrence Lanni, one of the gambling industry’s most powerful figures,” is stepping down from his executive posts after the newspaper started asking questions about Lanni’s academic credentials.

Although Lanni did graduate from USC with a bachelor of science degree in business back in 1965, he never earned the MBA in finance that is listed for him on the MGM Mirage Web site, according to USC officials.

And like all of these academic credential stories, this one follows a predictable pattern: When the executive is confronted by a long-standing but unsustainable academic claim, he changes the story a little in the hope that will help matters, even though in reality, it only makes things worse.

“Lanni said he took a series of classes toward an MBA, but didn’t finish because he went to work instead,” the Journal reported. “But he said he was awarded an honorary MBA from USC in 1992 when he was named Alumnus of the Year by the business school. ‘I understood I was given an honorary degree,’ he said. At USC, [a spokesperson] said the university’s list of honorary degrees didn’t include Lanni either.”

Another predictable part of this episode is the standard-issue claim that the lying excecutive’s departure has nothing to do with the foolish lie being discovered.  “Lanni, who is to leave Nov. 30, said his resignation was for personal reasons. … Lanni said, ‘I must stress that this issue has nothing to do with my decision.’ ”

This is a foolish fib that makes no sense. Lanni is, by all accounts, a stellar executive who “joined [the company] in June 1995 as president, chief executive and a [company] director,” according to the Journal. “He guided the company through periods of unprecedented growth, including mergers with Mirage Resorts and Mandalay Resort Group, [and] he was also instrumental in expanding MGM Mirage’s reach into the Middle East—personally negotiating a landmark partnership with Dubai last year that led to a $5 billion cash infusion from the Persian Gulf state’s investment arm to buy half” of MGM Mirage’s huge CityCenter project and a stake in the company.

I don’t know why Lanni did this, because whether he earned an MBA or not would seem to be inconsequential in the larger arc of his long career. But here’s my guess: He added the MBA reference to his résumé many years ago, when he felt it might help him. And then he forgot about it. After time went by, he couldn’t remove it since the reference had been on the résumé for so long, but on the other hand, he thought it would never be checked out. In his mind, it didn’t matter.

Problem is, it does matter. Lies and cover-ups always seem to bite people in a big way, usually much more than the original transgression itself. In fact, Terrence Lanni missed a golden opportunity to stand up and actually be held accountable here.

He could have set himself apart from people like Richard Fuld and all those Wall Street executives by saying something like: “You know, I put this on my résumé a long time ago when I felt I needed to, but it was wrong then and it’s wrong now. I don’t think it makes me any less of an executive or manager, but I should have never done it because lying is always wrong, even if I thought at the time that I was doing it for a good reason.”

Wouldn’t you love to hear an executive do that? I would, because I believe it would help restore some well-needed confidence in our corporate executives at a time when many of the people working for them believe that the top managers don’t live up to the company values they try to push on everyone else.

The problem with executives lying (or anyone lying, for that matter) is that it makes people think that if you lie about one small thing that you’ll probably lie about anything. That’s kryptonite to a company’s culture. It kills trust and destroys careers.

J. Terrence Lanni didn’t need to pretend he had an MBA. He built a great and accomplished career without it. Unfortunately, all those accomplishments will now always be clouded by a lie that didn’t need to be told. In other words, all the great good can be overshadowed by the little bad.

It’s a sobering lesson for everyone and anyone tempted to fib. In this day of Google searches and background checks, a little fib can come back to bite you in a big way.