Rudy Giuliani's daughter arrested for shoplifting. Why do girls shoplift?It's never about the lip gloss -- or is it?

When we heard that Caroline Giuliani, 20, had been arrested for shoplifting at a Sephora in New York City, besides wanting to know exactly what the Harvard senior tried to make off with (apparently some nice peachy blush, judging from the photo at left) we were dying to figure out: What's with all the cute, rich thieves?

Think about it: First Winona, then Britney, now the apparently sticky-fingered daughter of the former mayor of New York. Not to mention a few 20-somethings we know who dabbled in the art as relatively well-off teens.

"Who hasn't shoplifted at Sephora!?" said our friend Zoe*, 26, when she heard the news. "I had every Hard Candy compact that existed, and I wasn't even into glitter by that point."

She's also deeply indebted to Nordstrom's, if you know what we mean. So, why did she do it?

"I was just a white kid in an upper-middle-class suburb who had nothing to do but shoplift or smoke for cheap thrills," she says.

While boredom may play a part, we suspected there were more sinister reasons the girls you'd least expect were cashing in on the five-finger discount. And, as an expert explains after the jump, we were right.

Some people, says Donald Franklin, a licensed psychologist specializing in forensic psychology, do steal because they're criminals. They shoplift, he says, sell the merchandise, and pocket the proceeds. In other words, it's a business, albeit an illegal one.

Others have a bad case of celebrity envy:

"There is an old saying, 'We covet what we see,'" says Franklin. "When we live in a society where having lots of nice things seems expected, people have a sense that they want the same thing, that their life is going to be wonderful if they get this stuff. They're motivated by a desire to be like the people who everyone wants to be."

But then why, more often than not, are the cases we see perpetrated by the people who "everyone wants to be"?

"For the people who can afford it," he says, "it's often an impulse-control disorder -- they can't delay gratification -- and it's related to other psychological issues, particularly with relationships and self-esteem."

For some, adds Jonathan Alpert, a therapist in New York City, shoplifting is merely thrill-seeking. Think: bored teens.

"It's just a sort of defiance of the expectations of society," he says. "It's certainly not about the product. In some respects it might be about where there is a great risk and danger, there's a thrill."

Entitlement, both therapists say, definitely plays a role. "There's a see-it-want-it-gotta-have-it attitude," says Franklin.

But, in the case of a Caroline Giuliani, who's been rumored to be estranged from her father after his public and bitter divorce from her mom -- to the point where she famously joined Barack Obama's Facebook fans when dear old dad was also running for president -- shoplifting may be a petty form not of theft, but revenge.

"Sometimes the behavior is engaged in to embarrass other people in their life," says Franklin. "Particularly if you're related or married to someone who's extremely concerned about his image. In that case, it really is kind of wanting something to happen because they're unhappy, and it brings attention to the situation when they get caught," says Franklin.

In other words, Caroline may be forcing Sephora to pay precisely because she feels her dad hasn't.