A delicious smell can inspire cravings and lure passersby into a restaurant. McDonald’s put that power to the test by deploying a series of billboards diffusing the scent of its bestselling french fries.

Amsterdam-based agency TBWA\Neboko collaborated with Raúl&Rigel, a production company specializing in fabricating unusual billboards, to produce a series of unbranded, blank red and yellow billboards with a hidden compartment to store fries. An internal heat and ventilation system intensified the smell of the snack and directed it toward anyone walking within five meters of the display.

“The smell of McDonald’s is an iconic asset for the McDonald’s brand, as recognizable as its products, golden arches or jingle,” TBWA\Neboko chief creative officer Darre van Dijk told ADWEEK. “That made us wonder: Can we make an outdoor where the McDonald’s smell is the ad? So we wanted to test that a red or yellow billboard with nothing on it but the iconic smell could make people think of McDonald’s.”

An on-site experiment captured thousands of bystanders walking in front of the billboard and reacting to the smell. When interviewed after, most recognized that it was McDonald’s fries.

A “Smells Like McDonald’s” film shared on YouTube captured the exercise, noting, “People could look away, but they couldn’t smell away.”

“We can’t wait to develop new initiatives and experiments around the unique smell of McDonald’s,” van Dijk said.

All of the billboards were placed within 200 meters of a McDonald’s so that any cravings the display inspired could be easily satisfied.

“Smell has been proven to be more effective at sparking clear and emotional memories than images,” McDonald’s Netherlands chief marketing officer Stijn Mentrop-Huliselan said in a statement. “With the inclusion of this next sense in our advertising, we found a new way to remind people of good times at McDonald’s.”