Teachers and police in the UK have reported that pupils often seem naively surprised when they are caught. “How did you know it was me?” they wail, forgetting that it is not particularly subtle to film oneself bullying someone, then post the footage on the internet with your school’s name on it.

But dumber still are a pair of teenagers at Kopfholz school in Adliswil, Switzerland. A teacher managed to intervene midway through the attack they were carrying out on a 12-year-old pupil and filming on their mobile phones.

What gave away their cunning plan? The fact that they had printed posters and flyers advertising the happy-slapping attack in advance and handed them out to fellow students. The moment their target stepped into the playground, a large crowd gathered, which alerted teachers.

It remains unclear whether the Swiss pupils had simply missed the point of happy-slapping, or had decided to be innovative and transform it from a filmed event into live theatre.

Thankfully, the new version seems unlikely to catch on.