The challenge for Publicis Brazil was to come up with new way to warn young people about the evils of drugs and alcohol, and that's a tough one considering all the frightening anti-drug messages kids are subjected to these days.

The client was Mackenzie Presbyterian University in São Paulo in Brazil, and what the agency came up with was a graphic device that would stop students in their tracks, quite literally.

Walking across campus, students are confronted by a break in the sidewalk, as if a crew of workmen had come along and dug up the pavement (see picture, below).

Nearby, as if it were a construction site, there's a barricade with this message on the sign, in Portuguese: “That’s how drugs are: The end of the line. Stay away from drugs and alcohol.”

Confused students stop to read the sign and figure how they are going to go around the dug up area.

But as they stare in what appears to be an abyss they realize that the hole is not real at all but an optical illusion. What they're looking at is vinyl sheet on which the illusion of the abyss has been created.

The display is not hard to miss. It's up at several entrances to the university’s campus.

Guilherme Jahara, chief creative director at Publicis Brazil, says he doesn’t know how many of the university’s 30,000-plus students use drugs and or alcohol, but that it’s likely a high number considering the majority falls between the ages of 18 and 24.

“So we thought to use all of the campus area to do public education about drug and alcohol abuse,” Jahara says.

The campaign, which launched on Feb. 25 and runs through June, came about after four teams of creative directors and copywriters submitted their ideas to the client. The university then selected which it thought would generate the most buzz.

Besides being picked up by newspapers, online news sites and local TV stations, Jahara says the ads have also inspired lots of in-class discussion about drug and alcohol abuse on campus.