The plastic baby Jesus has been lobbed to the back of the stock room, the last traces of glitter have been swept from your classroom and everyone’s been on the Strepsils since Bonfire Night. This can only mean one thing: it’s time for the staff Christmas party. Finally, a chance to let your hair down.

But beware: the Christmas do can be a minefield. Gathering a group of knackered adults with stressful jobs together is a recipe for making tensions run high.

And when you throw some cheap booze into the mix, the fall-out can be apocalyptic, as Year 1 teacher Rachel Thomas (not her real name) discovered at her school Christmas bash.

“A Year 2 teacher and I had been sniping at each other since September,” she explains.

“It escalated because of a disagreement over nativity rehearsals and came to a climax at the staff party, where we had a screaming row over the turkey dinner.

“Everyone was horrified and we were taken to one side and told to calm down or go home. The kids in our classes behave better than that.”

Even when the atmosphere remains jolly, things can go very wrong, says Nicky Pearce (again, not her real name), a primary school teacher from Derbyshire.

“My teaching assistant and I drank every bottle of wine that we had received for Christmas from the parents,” she remembers. “We ended up in my classroom where we thought it would be hilarious to eat the class guinea pig’s food. The deputy head found my TA cackling on the floor with a half-chewed carrot and me going at the bowl of pellets like it was a dish of bar snacks. I don’t remember much after that.”

Let’s face it: whether you’re having a three-course meal in the local gastro-pub or a handful of Twiglets and a plastic cup of Lambrini in the school hall, there is always the potential for the party to end in tears.

And given the tendency of parents and pupils to pop up like meerkats out of a burrow at the first sniff of a drunken teacher, it is also highly likely that you will have witnesses to your behaviour.

But fear not. I’ve compiled a list of dos and don’ts to make sure that you avoid disaster. As the Christmas party seems to make everyone act like children, I’ve borrowed some classic primary-teacher phrases to help ram the message home.

1. ‘Off you go, it’s breaktime’

You’ve had it up to here with assessment, behaviour problems and troublesome parents, not to mention all the marking you’ve got to do, but now is not the time to talk shop. Take a deep breath, let it all go and talk about something else.

2. ‘Play nicely’

You probably loathe one of your colleagues, usually for completely acceptable reasons (such as, she takes all the Blu-tack from the stock cupboard and hides it). But don’t bitch about her all night; don’t argue with her; just keep your distance and let bygones be bygones. (Sneaking into her classroom, locating the Blu-tack stash and using it to fashion a hand with the middle finger sticking up probably counts as a grey area, though. Do that.)

3. ‘Stop showing off’

Don’t attempt to use the Christmas party to get a promotion. It is not the time to disarm the senior leadership team with tales of your many successes. They want to let their hair down, too, so stop sucking up to them and enjoy yourself.

4. ‘Put that device away - it’s not computer time now’

Do not upload those incriminating photos to Facebook unless your privacy settings are 100 per cent watertight. A picture of the Sendco drunkenly flashing her knickers or the Year 5 teacher vomiting into a Santa hat will be passed around social media before you can say “disciplinary action”.

5. ‘If your friend told you to jump off a cliff, would you do it?’

Jill from reprographics might want to do body shots, but I’m pretty sure that you don’t.

6. ‘Don’t be a bossy boots’

Not everybody drinks alcohol, so respect that and allow people to enjoy the Christmas party in their own way.

7. ‘We don’t do kissing in school’

If you’re trying to engineer a romantic liaison between you and a colleague, stick to the golden rules: be discreet, check that you’re both single, and remember that you’ve got to work with this person for the foreseeable future, however things turn out.

8. ‘We keep our hands to ourselves’

Keep your temper in check or it can end in a playground-style scuffle or worse. And nobody is going to care who started it.

9. ‘Nobody is allowed home without a responsible adult’

In this case, a taxi driver counts as a responsible adult. Do yourself a favour by booking a cab and, crucially, getting into it when it arrives for you. Time at the bar, please, ladies and gentlemen.

Lisa Jarmin is a primary teacher in the North West of England