Pupils are being allowed to swear at one Northamptonshire secondary school - as long as they limit their use of bad language to five times a lesson.
A tally of how many times the f-word is used will be kept on the board.
Parents of children at the Weavers School in Wellingborough were told of the new policy in a letter, according to a report in the Daily Mail.
The policy, which comes into effect when term starts next week, has been condemned by parents' groups and MPs.
"In these sorts of situations teachers should be setting clear principles of 'do and don't'," said Nick Seaton, chairman of the Campaign for Real Education.
But headmaster Alan Large said he had received no complaints about the policy.
"The reality is that the f-word is part of these young adults' everyday language," he told the Daily Mail.
Assistant headmaster Richard White said the policy was aimed at two classes of 15 and 16-year-olds that were particularly unruly.
"Within each lesson the teacher will initially tolerate (although not condone) the use of the f-word (or derivatives) five times and these will be tallied on the board so all students can see the running score," he wrote in the letter.
"Over this number the class will be spoken to by the teacher at the end of the lesson."
The school, which has 1,130 pupils, also plans to send "praise postcards" to the parents of children who do not swear in class.