WHEN he pitched his idea for a reality movie around Hollywood 18 months ago, Jonathan Murray – creator of the hit MTV series “The Real World” – was met with a chorus of “no thank yous.”

But he persisted in shopping “The Real Cancun,” which follows 16 uninhibited college students as they frolick in sun-soaked, tequila-drenched Cancun, Mexico – and finally found a backer in New Line production exec Richard Brennar.

Now it looks like they have a hit on their hands.

The Internet is already buzzing with anticipation over “The Real Cancun,” which opens Friday.

Film-fan Web site Aint-it-cool-news predicts the film is “going to make a . . . load of cash,” and Paul Dergarabedian, president of box-office tracking firm Exhibitor Relations, also expects the movie “will do very, very well.”

“Reality is red-hot right now, and this is a light, frivolous, fun movie aimed directly at a target audience – 18- to 24-year-olds – with a lot of money to spend,” Dergarabedian says.

“The Real Cancun,” which will be released nationwide on 2,100 screens, is rated R for a reason.

Producers installed more than 100 surveillance cameras in Cancun’s Hotel Baccaka and followed the young people as they participated in wet T-shirt and “hot body” contests, downed endless tequila shots, took communal showers and got busy.

Infrared cameras kept filming when the action moved to the bedrooms, resulting in shadowy – but uncensored – footage.

“The Real Cancun” was originally slated for the summer, but it was fast-tracked when Universal announced plans – since postponed – for a May 9 release of a rival spring-break reality picture, filmed in Cabo San Lucas by “Joe Millionaire” creator Mike Fleiss.

That left Murray and his team just one month to pull together the footage.

“The one fear we had was it could end up being a movie about a bunch of people drinking and behaving badly,” Murray says. “That might be a home video, but it’s not a movie.”

“It was well-planned, well-cast, we had great camera people – and then we got lucky.”

“The Real Cancun” has a surprisingly engaging narrative – it’s part coming-of-age film, part romance, part teen sex comedy, with a bit of “Girls Gone Wild” thrown in.

The handful of core characters include Alan, an 18-year-old Richie Cunningham type from Texas, who has never had a drink and is extremely shy around girls; Paul and Jorell, two hilarious African-American friends from Los Angeles and Heidi and David, a couple in their senior year of high school who are poised to take their platonic friendship to another level.

“What’s so funny is these real people ended up being similar to the characters you would write in one of those teen comedies,” Murray says.

But you can’t make this stuff up.

“It’s so hard to write something that feels real to an audience that has been raised on reality TV,” Murray says. “For us to have written a scripted spring break film would have been incredibly hard, and it would have turned out pretty mediocre.”

Casting was crucial.

Sasha Alpert, who has cast five seasons of “The Real World” and four seasons of Murray’s other reality series, “Road Rules,” held open calls at colleges.

“We were looking for personable people, of course, but we were also looking for people with stories,” she says.

“We were looking for people who would go down there with a purpose – the ideal person for a reality show is someone who is about to go through a big change.

“But, of course, they had to have an ‘arc’ that wasn’t going to take 25 weeks of filming – it had to be something that’s going to happen during a trip to Cancun.”

“The Real Cancun” came in with a budget under $10 million – a cast member said they were paid about $1,000 each – which suggests it could open the floodgates on a bonanza of similar projects.

Not so fast. Regarding inevitable imitations, Murray says, “I think they should approach it very cautiously.”

He says only a limited number of subjects lend themselves to the genre.

“Some things like spring break are perfect: It’s an eight-day event, it has a beginning and an end and people come with specific goals – it’s a simple, clean story for us to tell.

“But we’ve been wracking our brains for ideas for other reality movies, and we can’t think of many.”