Update: Gizmodo has published an investigative article into Dr Damian Jacob Markiewicz Sendler. They claim he is a “fake sex doctor”, a “serial fabulist”, and has lied about many of his certifications and awards. Please read the in-depth piece by Jennings Brown here to learn more. IFLScience reached out to Sendler as well and received comment, which we’ll be updating shortly. A statement on his site can be found here.

Science has no boundaries. Everything is up for investigation, to a degree – from the most massive galaxies to the smallest critters. This often yields incredible discoveries, but on occasion, it can produce some scientific papers with some rather unexpected, and incredibly bizarre, subjects.

There are peculiar papers out there that have claimed “cats understand the basic laws of physics,” or very obvious studies that conclude that “being homeless is bad for your health.” Sometimes you get a combination of both – a study once concluded that there’s a benefit to having higher quality colonoscopies. You know, as opposed to those $5-a-pop ones.

However, a study was recently brought to our attention that clearly takes the biscuit for having the most not safe for work (NSFW) title of all time. The paper is both ludicrously specific and intensely detailed, and we’d like to share some details of it with you now. Be warned: This isn’t for the faint-hearted among you.

The title of this paper, published in the Journal of Forensic and Legal Medicine, is: “Similar mechanisms of traumatic rectal injuries in patients who had anal sex with animals to those who were butt-fisted by human sexual partner.”

That, as you can imagine, is the sort of paper that takes you down quite the rabbit hole – no, not like that. While that title is sinking in, burning itself indelibly on your imagination, let’s take a look at the abstract, shall we?

“Sexual pleasure comes in various forms of physical play, for many it involves stimulation of the vagina, while the anus for others; some enjoy both.” So far, so sensible, but then the paper – which looked at a small number of people who are attracted to animals – starts to get a little heavy.

“Among zoophiles, the mode of harm occurs through blood-engorged, interlocked penis that causes tissue lacerations upon retraction from an anus,” it notes. “In people experimenting with fisting, repetitive stretching within anal canal and of external sphincter causes the internal injuries.”

We are so, so sorry. Volodymyr Tverdokhlib/Shutterstock

Following on from what could be one of the most graphic passages of text in a scientific paper to date, the study then emphasizes that in fisting, the pressure applied by hand is controllable proximally around and within the anal sphincter, while penetration by the animal penis is unpredictable and occurs within the proximal anal canal.

The entire paper goes on like this. It’s not clear what the impetus behind this rather niche piece of research was, but it’s safe to say that it’s nothing less than an extreme look at the nature of certain people’s, well, extremities.

Anyway. Hopefully this scientific look into the troubles of people’s poo portals hasn’t soiled your mind too much.

You have no idea how difficult it was choosing the images for this post.