The Mile-High Club isn't an actual membership club, but it's a very real phenomenon. Also known by its initials MHC, the club is made up of people who have had sex in the air. You don't need to have fucked a stranger in the toilet of a commercial airliner, although that's the classic image of an MHC encounter.
All it takes is the experience of sex in a plane, helicopter, or even an airship. It's also a surprisingly old club which long pre-dates the Wright Brothers. As soon as the Montgolfier Brothers launched their famous hot air ballooning career, London magazines started advertising for people willing to "fuck" in the air (the 18th century was a liberated age, if you had money).
However, the term itself was invented by millionaire playboy and pilot Lawrence Burst Sperry in 1914. Sperry found that being aerial seemed to stimulate his desire for sex, and many people have followed in his footsteps, but why?
There's no one explanation for the popularity of the MHC. Some people link it to the vibrations or aircraft, which supposedly heighten the sexual ecstasy experienced by participants.
For others, it's the fact of having sexual intercourse in a confined space, far from the ground, almost in the heavens.
Others seem to enjoy fucking in enclosed cabins with their fellow customers slumbering nearby, and some even get a kick out of having sex far over the ocean, miles away from international borders.
Then there are the staff of the planes involved. There's a reason why kinky stewardess uniforms never go out of fashion. For example, actor Ralph Fiennes once inadvertently caused a Qantas stewardess to lose her job when it was found that they had sex on an intercontinental flight.
Surveys of plane staff have also found that 21 percent report engaging in sexual activity when on duty. Being in the air just seems to have a magical effect on people, there's no getting away from it.
If you want to experience some intense aerial eroticism, there's a right and a wrong way to go about it.
First of all, look for the signs that people are interested in joining you in the cabin toilet. They won't always be upfront about it. A gesture, a wink, a scribbled note is sometimes all it takes for strangers to creep their way to the toilet as the cabin lights dim.
It's also a good idea to take contraception on every flight - as you just never know.
And don't assume that the sexy stewardess on board is only being nice for professional reasons.
14 percent of airline staff report having sex with passengers at some stage in their careers. It does happen!
Finally, don't be embarrassed. Sex on board happens all the time. If you are caught, finesse it out and try again next trip.