It would be nice to pretend that it's nostalgia, but we all know the real reason we like to put ourselves through the ritualistic torment of a school reunion: a pathological thirst for the failures of our peers.
Yet what seemed like a good idea when you signed up turns out not to be such a good idea when cornered by your horrendously irritating former classmate as you drink bad white wine at midday, and the question "So what are you up to at the moment?" hangs like a loaded gun in the air.
In such situations, there is an unspoken contract that sees most people agree to be fairly low-key when it comes to documenting their successes. The problem is, there are always a few narcissistic renegades who shun this social practice in favour of unapologetic, unbridled boasting about their lives.
Unless you a) are pregnant, b) got engaged in the past 48 hours,or c) just been shortlisted for the Booker, it is unacceptable to shove your good fortune in everyone else's face. Forget the dullards: it's these people who are the real vipers of reunionland, serving only to make others feel intensely maudlin about life – particularly when three glasses of Jacob's Creek to the wind.
Oh, the intense irritation of shuffling around, being silently judged by 60 of your peers in a Dante-esque circle of hell – it's no way to spend a Saturday afternoon.
Damn that impertinent curiosity that dragged us there through the traffic. And damn it again for inevitably dragging us back in another 10 years…