Teenagers copying TV shows are among dozens of kids excluded from Lincolnshire's schools for "sexual misconduct".
Education bosses say a number of secondary school boys have been exposing themselves in a test of strength and manliness.
Lincolnshire County Council told the Echo that the pupils involved would expose themselves and inflict physical pain on one another to see who could withstand the most punishment. In some cases, drawing pins have also been involved. They are among 25 secondary school pupils hit with fixed period exclusions for sexual misconduct in the academic year 2010-11.
A further 12 were excluded from academies and seven from primary schools.
The figures were released following a Freedom of Information Request from the Echo.
Phil Whitworth, education out of school team manager for the county council, said the young pupils had copied a television show.
"It comes from those silly TV things where men see how much pain they can put each other through. We class it as sexual misconduct and we deal with it with fixed-term exclusions," he said.
Mr Whitworth said the list of criteria for sexual misconduct exclusion was "a mile long".
He said: "Some of the exclusions are down to pranks but some issues can be quite serious – especially in secondary schools where things can carry over from the weekends."
TV watchdog Ofcom said it had received complaints from Lincolnshire people about extreme, punishment-based TV shows, but said they did not break any rules as warning messages were screened before each episode.
Other examples of sexual misconduct given by the county council include harassment, bullying and graffiti.
Jule Holmes, a 47-year-old mother of two from West Parade, Lincoln, said she believed the schools were taking the right course of action.
She said: "As much as we try, we can't always stop our kids from picking things up, whether it's from the television, the internet or even their friends.
"Whatever these teenagers are up to sounds juvenile and outright disgraceful and maybe being sent home from school for a few days is the only way to show them that.
"If kids are getting their bits out at school and are hitting
them, then it's going to be disruptive for everyone around them. I think I speak for all parents when I say I wouldn't expect my kids to put up with an environment where that kind of behaviour is going on.
"Sometimes something as severe as an exclusion is the only way they learn."
The Echo's Freedom of Information request also revealed that more than 840 pupils were excluded from school in 2010-11 for verbal abuse or threatening behaviour towards an adult – the most common reason for an exclusion.
Around 780 were excluded for physical assault against another pupil and a further 379 were excluded for persistent disruptive behaviour.
There were also more than 140 exclusions relating to drugs and alcohol – including possession and pupils arriving at school under the influence of substances.
Nigel Appleton, dean of teacher development at Bishop Grosseteste University College, said: "Our experience is that schools in Lincolnshire do use exclusions in an appropriate way and if a pupil gets to that point, it's because they've come to the end of a very long road."