Single girls are welcomed with open arms – and are even offered free entry. But sorry lads – single men are banned from most parties.

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The girls are usually bisexual – or at least bi-curious – and absolutely stunning.

They are often foreigners – with a lot from Eastern Europe, Brazil, South American and the US.

Many blokes take viagra so they can keep up with the fun after they have cum the first time.

Guests don't usually exchange names or phone numbers and only indulge in their secret indulgence behind the closed doors of the club.

A guy who has attended a lot of different parties said: “Usually they're gorgeous.“Some of them are the most beautiful women you can imagine.”One girl told the Daily Star Online: "The men definitely get the better deal." Guests make small talk over cocktails and for some reason there is often a buffet – which always goes untouched.

But everyone is really checking each other out – because at midnight all hell breaks loose.

Did you know these sex parties are even done live on webcam.

This way random visitor can enjoy this hot orgy or gangbang on a live stream.

Sex mad couples have elected for a wife-swapping bonkathon as the nation goes to the polls on the Brexit referendum.