Residential trips can bring out the worst in people: they can be uncooperative, aggressive, argumentative and just downright difficult. And that's just colleagues. Pupils can be worse and parents - or one of them - can be the worst of all.
I realised that a residential trip with a group of Year 11 pupils was going to be a challenge. This was a "difficult" year group, and colleagues were not exactly queuing up to join the trip - an outdoor pursuits type, designed to allow the maximum expenditure of pent-up energies.
So we took the risk of extending the offer to one or two parents. Of course we did all the checks, but the CRB doesn't reveal personality flaws that are only apparent on school trips and one of our co-opted adults was thus afflicted.
He was - to be frank - a great big kid. He wanted to do everything and be the centre of attention. He abseiled, he pot-holed, he mountain-biked. He was 100 per cent involved, which is great unless you are expected for some of the time to take a back-seat and supervise others.
But, no, this guy was Action Man. Not only this but he was intensely competitive and had to be the first, the fastest and the fittest. This meant that he was constantly throwing out challenges to the apprentice alpha-males (of whom there was no shortage) and egging them on.
Inevitably this led to a broken ankle. Unfortunately it wasn't his. Yours truly had an evening in AE with one of the lads awaiting X-rays and then explaining to parents, completing the paperwork and generally being confined to base.
Meanwhile, the cause of the trauma was swinging from ropes and whooping with delight and behaving like a 12-year-old. I vowed that if I ever had to bring parents again, they would be the sedentary type and built for comfort, not adventure.
The writer is head of PE at a secondary school in London. Send your worst parent stories to firstname.lastname@example.org and you could earn #163;50 in MS vouchers.