You know those disclaimers they put at the end of movies? "No animals were harmed in the making of this motion picture." Or, "Any resemblance to actual persons, living or dead, is purely coincidental." Well, this is the JC equivalent. "None of the grotesquely over-the-top barmitzvah celebrations about to be mentioned in this column were attended by me personally."
I want to stress that point, lest any friends or relatives suspect - heaven forbid - that I am criticising them or the wonderful parties they threw to celebrate their equally wonderful children. The evidence I place before you today is, I'm happy to say, second-hand. But my sources are utterly reliable.
Let's begin with the invitations. I come from the era when a stiff slice of embossed card dropped through the doormat was about as OTT as it got. How quaint that seems now. Today's barmitzvah invitations are too heavy to be left to the mere Royal Mail. No, a courier arrives, sweat beading on his brow under the weight he has to carry. He hands you a parcel that is padded and requires a signature.
Inside is no mere card. I've seen one as thick as a book. It opened to reveal not a message, but a small TV screen - the same proportions as a smartphone - which instantly played a short, professionally produced film, starring the barmitzvah boy of course, summoning the recipient to his party. As it happens, that one landed in the hands of a friend in the advertising industry, who estimated that each invitation would have generated a "unit cost" of at least £40 - and that's before you reckon with the hernia-suffering courier.
More shocking, though, was the invitation that came via cost-free email. Written rather sweetly, it saw the barmitzvah boy invite seven or eight of his closest friends to join him on his family's private yacht for a week of Mediterranean fun. The boy's parents would not be there, but there was no need to worry: the children would be fed and entertained by the skipper and his 12-person crew, including personal chef.
But what of the parties themselves? YouTube offers ample evidence of the scale of the modern simcha. A video of a Dallas boy celebrated by a Las Vegas-style stage show involving a troupe of female dancers - culminating in the child being lowered from the heavens to join them - went viral a couple of years ago. But British Jewry is catching up.
The humble speech is now replaced by a lengthy film, often a music video, made to Hollywood standards. I've seen one involving actors, specially composed music, locations and costume that could not have come in for less than a six-figure budget.
You might think that if people have this much money, who really gets hurt if they spend it in this way? My anxiety is not that some of these parties - with their hired women, paid to dance semi-nakedly - suggest less a time-honoured Jewish tradition than the last days of the Roman empire.
Nor is my chief concern that an outburst of extravagant materialism is a jarring way to mark the passage to Jewish adulthood.
Don't get me wrong. I'm no killjoy. A party, with good food, good music and good company, is positively life-affirming. But I have a worry best described as ambassadorial. Several of the sources of the evidence set out above were non-Jews: friends who had been stunned by the display of sheer excess they had witnessed. For many of our fellow Britons, this will be the only Jewish ritual they will ever experience. What kind of face do we think we show the world when we show them this?