We've heard of the Mile High Club, but that normally happens in the privacy of the bathroom, right?
Well one couple on a Ryanair flight appeared to have no regard for anyone else and enjoyed a romp right there in their seats.
The woman straddled the man in his seat, and witnesses said they saw them undressing.
According to SF Gate, one traveller, Kieran Williams, 21, said: "They seemed so drunk, they brought a lot of attention to themselves.
"You could see the girl taking off her pants and he pulled his trousers off. She started riding him."
He said he had heard the couple talking about doing it, but thought they were joking.
The Daily Mail reports that he added: "A woman was sat next to them and she stood up and asked if she could be moved. About twenty minutes after it happened, someone complained about it. But the crew did nothing.'
Speaking to the Daily Mail, a Ryanair spokesman said: "We are looking into this matter.
"We will not tolerate unruly, disruptive or inappropriate behaviour at any time and any passengers who appear to behave in an unacceptable manner may be liable for further sanctions."
The footage has been uploaded to YouTube and LiveLeak and a number of people commented.
One wrote: "Anyone else turn into their parents? I used to laugh at stuff like this as a younger person and find it to be funny, now it's a reflection of society and how immorally disgusting people are. Get a f****** room, no one wants to see it, especially me. It's a plane, not a f***-fort."
Another joked: "Ryanair charge extra for f****** in your seat", while one laughed: "Definitely not Virgin Airlines!!", and another said: "Disgusting behaviour... flying Ryanair."
Another said: "Hope kids weren't on the flight...PIGS."