The Petite Syrah café in Nice recently instituted a payment policy where the price of a cup of coffee is determined by how the customer requests it.

“A coffee, please” will cost you a middle-of-the-road €4.25 ($5.85). Drop the “please,” and you’ll find yourself paying a whopping €7 ($9.65) for a cup.

But add a simple “bonjour,” and you’ll find yourself shelling just €1.40 ($1.95) for your morning joe.

“I know people say that French service can be rude but it’s also true that customers can be rude when they’re busy,” shop owner Fabrice Pepino told The Local. “It’s our way of saying ‘keep calm and carry on.'”

What started out as a joke to poke fun at the stressed-out lunchtime crowd has had an amazing effect on people’s politeness levels, Pepino said.

“Most of my customers are regulars and they just see the funny side and exaggerate their politeness,” he told the site. “They started calling me ‘your greatness’ when they saw the sign.”

Looks like Pepino is going to have to start charging a sarcasm tax.