It's the annual ball for our sixth-form boarding house. Last year's event was a catastrophe of fixed-term exclusions. This year, I am just at the point of contemplating how awkward it is to be sober and motionless on a dance floor when two girls approach, gabbling that there is something I need to see but they need me to be "cool about it". Those dreaded words.
Upstairs, a student, Jake, is flopping around on the carpet of his room like a fish in a boat.
"I'm not fucking drunk, I just need to puke and then I can go back down," he mumbles, rather optimistically.
The girls insist that he has consumed nothing more than the school-sanctioned wine at dinner. It seems a little far-fetched but I trust these students. I decide, perhaps stupidly, to put them on nursing watch and ask them to tell me if Jake leaves the human end of the colour spectrum.
I head back downstairs. On the dance floor, the boys are wearing leopard-print onesies and bumping and grinding with each other in a way that makes you think school homophobia is on the wane. The girls, elegantly made up, look on disdainfully.
No one ever wants to staff a student party. It's not just that you don't want to give up your Friday night. It's not even the disturbing realisation that somewhere along the line you have turned from party-goer to party-policer. No. It's far more the dread of having to forcefully disentangle groaning youths, either from each other or from vomit-strewn carpet tiles. Without doubt, things go wrong at student parties. But occasionally you get a rare insight, one that you would not have got in any other circumstance, which makes it all worthwhile.
Later on at the party, I find myself having some of those confessional conversations that teenagers seem so eager to have, one of which stays with me for a long time. An able but lazy student, Chantelle, with a penchant for make-up and boys, tells me why she's not bothered about university.
"Come on, Sir, you and I both know I ain't cut out for all that academic bollocks. And besides, it's not like I need it to be an air hostess, is it?"
"Is that what you want to do?"
"Yeah, for sure ... But what else could I do, anyway?"
This is the first time I see that her "laziness" is actually a self-esteem issue and that university is a fearful spectre. I know Chantelle's capabilities and I am able to convince her that she could do fine on any number of courses. We decide that if she still wants to be an air hostess then that's brilliant, but it might just be worth giving herself some options.
It is at this point that I discover Jake has left his room and is trying to throw framed photos of the headteacher's children out of the window.
In a nutshell, that is what policing a party can provide: the obligatory drunk students, and the insights and conversations you would never have got otherwise. Perhaps surprisingly, they are equally important. The off-diary advice and the controlled experimental environment are key to guiding students through those tricky adolescent years. That's not to say that playing bouncer to a group of 16-year-olds is easy, nor that these benefits are a given.
Here are my three top tips for surviving school parties and coming out of them with positive experiences. They are also a rather good justification for not lobbying against parties and instead always being willing to volunteer to help run them.
1. Be prepared to look like an idiot
If you find yourself breakdancing in a circle of baying teens or crooning along to a Bruce Springsteen anthem that only you and the IT manager remember, well, just go with it. Because being able to laugh at yourself is the sine qua non of building relationships with teenagers. And, trust me, they will respect you all the more for it on Monday morning.
2. Be prepared for the rough edges
In this risk-assessed world of ours, it is perhaps understandable that many schools sidestep the hazardous environment of teenage parties. But it is a terrible mistake. Teenagers will drink, experiment and cavort irresponsibly as surely as night follows day. How much better, therefore, to make sure that it's wine they are drinking (not vodka and Red Bull chasers), that they get home safely, and that there is someone on hand to call an ambulance in the worst-case scenario (yes, that can happen, too). If we don't offer them a place to test boundaries then the outcomes could be far, far worse.
3. Be prepared to enjoy yourself
Regrettably, the pressures of work limit the possibilities for just getting to know each other, which is what makes those fleeting moments of "out of school" socialising all the more precious. This is where student and teacher can begin to see that the other is human, too.
Nelson Thornberry is a pseudonym. Formerly a secondary school teacher in the UK, he currently teaches at a school in South East Asia.