Female students at the Queen of Peace High School in North Arlington, N.J., stood up during homeroom Friday, raised their right hands, and recited a pledge in unison.
"I do solemnly promise not to use profanities of any kind within the walls and properties of Queen of Peace High School. In other words, I swear not to swear. So help me God," they said.
Meanwhile, boys at the school were free to use whatever language they wanted.
The co-ed Catholic high school started a civility campaign in concurrence with National Catholic Schools Week to try "to go back to some old fashion values," resource room teacher Lori Flynn said.
Flynn told ABCNews.com that for the month of February, girls at the school were asked to try not to curse. While their language wasn't a serious problem, she said there were plenty of instances of "subtle swearing."
Female students were given pins with a red slash through a pair of lips to wear. While Flynn thought the no-cursing crusade would come off as a joke to many students, she was surprised by their positive reactions.
"They said, 'This is serious. We're going to do this Mrs. Flynn, we love it!'" she said. "They put their buttons on and took the pledge seriously."
In addition, Flynn said the school put up polite zones posted near the school's chapel and by the main office where many parents came in.
But some boys at the school felt snubbed, she said, when they weren't asked to take part.
"It was supposed to be a really sweet, innocent, special treat for the ladies specifically for the month of February kind of thing," Flynn said. "And I guess it made the boys feel a little slighted."
But the school soon distributed buttons for the boys to take part as well.
"A lot of the boys said, 'I have to excuse myself, there's a lady present,'" Flynn said.
Even though the no-cursing ban was only instated on Friday, Flynn said she's already received a phone call from the all-boys Seton Hall Preparatory School in West Orange, N.J., about instating their own civility code for the month of Lent.
Flynn said the school was just trying something new with the no-cursing ban, which is technically over for female students on March 1. But if students wanted to continue the clean language crusade, "we'd bring it on the boys, and then we'd do a whole entire Queen of Peace campus with no swearing."
"We're just starting here," Flynn said.