The British stag party has changed in the past 10 years. The drink down the pub with dad or your mates is gone. It has been replaced with three or four nights in a foreign city, far from prying eyes and geared to meet the stag party's every desire.
And that is often much more than a visit to a strip club. For a large number of stags, visiting a prostitute has also become part of the ultimate lads' weekend.
Prague has 70 brothels and numerous strip clubs. It is not hard to find some of the half a million stag visitors, many British, that the Prague tourist board say visit every year. I found them at every sex establishment I went to.
There was a strip party bus, lap-dancing, and even a brothel that offers free sex provided you agree to be filmed. And many of the British stag groups had at least some, if not all, members buying sexual services.
A local charity worker was in no doubt that British stag parties coming to Prague had increased local demand for sexual services.
"If a British stag sleeps with women in a brothel or sleeps with her on the streets it could be a women brought… because of the sex industry, to be trafficked there from any part of the world."
The Czech Republic has long been a transit point for the trafficking of women in and out, and I wanted to find out how easy it would be to buy trafficked women for the sex trade.
Through contacts in the criminal underworld, we managed to arrange an undercover meeting with a trafficker. Posing as a London brothel owner, I arranged to meet him at a motorway service station.
As I secretly filmed our meeting, it became clear how straightforward the deal would be.
"I have two girls here for you now. That I can give to you. They have papers, they can travel you know, no criminal record, anything," he told me.
In the world of international sex trafficking, the leasing of girls has become common and it is big business.
"One girl makes me 90,000 krona (3,500 euros, £3,119) a month - around 50,000 euros (£44,561) a year. You give me 3,500 euros per month and I will come and visit you every month in England and collect the money every month."
The meeting lasted 20 minutes, and I could have bought two women...