There is nothing like a sign to stop kids from doing things they shouldn't. Whether it be "no ball games" on a patch of grass or "no heavy petting" in a swimming pool, signs have for centuries said one thing, only for young people to do the opposite.
The latest example of signage being put to brilliantly pointless use is to be found at Harris Academy Upper Norwood in South London, which has deployed "no slang" signs in corridors.
In a bid to halt sliding standards of the spoken word among its student population, the school has decided that all slang must be strictly forbidden. Its list of banned words includes "bare" (to mean "very"), "innit" and - undoubtedly the gravest of offenders - "yeah".
But is using this kind of colloquial language so very bad? Isn't it better to encourage young people to express themselves and embrace the linguistic variety of their mother tongues? And besides, teenagers have always corrupted standard language to distance themselves from adults - the majority grow out of it, anyway.
Perhaps the school would be better off teaching students how to switch between modes of speaking depending on the social context - a job interview, perhaps, or even a school corridor. Innit?