Katy Guest: The stagflation index is at an all-time high

In the various indices that measure the cost of living, has anyone looked at the inflation-busting rise in the price of the average stag night? You know how it goes: once it was an evening with the lads, a sniff of the barmaid's apron and turning up to the wedding with a guilty expression and one eyebrow. Now you have to book a long weekend, hire a paintballing centre, join the RAF, commandeer a £10m Chinook helicopter.

Poor Wills and Harry found out the hard way last weekend what a strain on the pocket other people's weddings can be. Not only will the princes have to attend their cousin Peter Phillips's nuptials in May, shell out for return fares to Windsor Castle, shop for fetching hats and find that the only thing left on the wedding list is an unidentifiable item of dining room furniture costing £179.50.

They also had to go through the wallet-draining ritual of the stag weekend: shacking up in an Isle of Wight hotel, having their pants pulled down, drinking bitter and Red Bull through a hose and funnel and daring local girls to hang CDs on their nipples. (The house record was eight, apparently, but Cowes girls practise by pickling their nipples in vinegar much like little boys used to do with conkers.)

Not everything fell under the rule of droit de seigneur, however, and locals were impressed to see the brothers paying for their own drinks with real money, at an estimated £3.10 per pint. That stacks up when you're necking it in industrial quantities through a hosepipe.

Prince Harry reported that he'd had an "awesome" time, but that it would take a while to recover.

He should worry. For those of us who don't have access to an RAF helicopter to fly ourselves to the venue, this escalating trend for lavish stag and hen parties is leading to a credit crisis. No longer are brides and grooms satisfied with lager, strippers and lifetime bans from the local tandoori to launch them into married life.

Now they want a week in Rio with dancing girls and a Turkish massage for 16. And William and Harry are only in their early twenties – they may be less enthusiastic when they're 35 and have been subjected to hosepipe cocktails and public wedgies every other weekend for years.

According to excited reports, the Phillips party included another insidious modern stag night phenomenon: girls. It used to be only gay men who were expected not only at the stag do but at the hen weekend, too. One couple I know went to 17 weddings last summer – they managed them, as well as the raucous stripping and puking weekends away, but they haven't been able to afford to eat yet this year.

Gay couples can now make up for lifetimes of strictly enforced feather boas and Lambrini with stag and hen nights of their own. So thank goodness stag towns across the world are cracking down.

Dublin drew the line in 1998 when it banned large groups from the Temple Bar area. Now incontinent stags are finding themselves incarcerated in Riga, and Krakow bar owners won't serve Brits in a state of undress.

No wonder the royals are flocking to the Isle of Wight – and no doubt the rest of us will follow. Just charge up the Visa, wear clean underwear and, for God's sake, make sure you don't forget the vinegar.