While most teachers have spent their holidays having a well-earned snooze and watching DIY videos on YouTube, there is always one bright-eyed and bushy-tailed colleague desperate to tell you about their life-changing trip to Peru.
Tanned, relaxed, possibly nursing the remnants of an unpleasant digestive condition contracted in the Amazon rainforest, they are the ones to avoid on the first day of term. Their stunning holiday snaps - prominently displayed in the staffroom - serve only to emphasise how you have frittered away the only extended chunk of free time you will have until summer 2014. Their interminable tales of teaching orphans in Tanzania show them in a saintly light, but are a tad annoying to those who spent six weeks grouting their bathroom in Cumbernauld.
It's not the far-flung sojourns themselves we begrudge - the problem is listening for half an hour to anecdotes about Australian crocodile farms or Canadian camper-vanning. It's the start of term, you know, there are lessons to plan and youths to chastise.
Tell people about your trips, staffroom holiday bores, but keep it short. Otherwise you deserve a stay on the naughty step. The headteacher sets a good example: he's too busy to bang on about his four weeks playing petanque in Provence.