College sophomore Jenna Schwartz is usually well-stocked with Red Bull when she enters the library during midterms.

But she's not always trying to stay up all night writing a paper - the energy drinks are for her peers.

Promoting the drink is her job as a paid campus representative for Red Bull.

Red Bull is one of a handful of companies that hires students to promote their products at college campuses, and, at Penn, students represent companies ranging from Apple to American Airlines to Playboy.

"If someone close to you is into something, you'll be more apt to try it," said Schwartz, who also gives out the drinks at various campus events. "People who attend the school know better what's going on on campus."

Though the use of campus representatives is nothing new, Wharton Marketing professor Jonah Berger said companies are increasingly making the move from print advertisements to interactive marketing strategies.

"People are more interested in buzz and word of mouth," Berger said. "Having campus reps makes it a little more of an interpersonal interaction."

The reps typically help companies sponsor campus events or distribute and hype up new products.

As an American Airline rep, Wharton junior Felisha Liu recently handed out discount codes for flights at a football game. If there is a big event on campus, she gives the event sponsors an airline ticket to auction off.

As a rep for Apple, College senior John Kneeland, a former DP blogger, sets up a booth at Computer Connection to promote Apple products.

Or, as he describes the job: "sit around, look good, use a Mac."

And the activities aren't always strictly commercial - Schwartz recently helped promote a local contest for people to make art out of Red Bull cans.

In addition to helping companies reach their consumers, student reps also can aid their employers' understanding of new trends and consumer desires.

American Airlines began a campus rep program at Penn last year to do just that, said Vanessa Conley, the airline's campus-rep operations manager.

"Every target demographic is different, and the student knows the student body the best," Conley said, adding that "their students will become the next business travelers."

The job has its perks for students, too: Liu can fly for next to nothing on American Airlines and often gets bumped to first class, and Kneeland gets temporary use of a Macbook in addition to lot of other free Apple swag.

They get marketing experience, too, but, according to Berger, being a campus rep is more than that.

"People love to spread rumors and stories and things like that. People like to be the first person who knows about a new band or a new style," Berger said. "It gives them a chance to be on top of what's happening next."