Sounding is one of those rare fetishes that doesn’t sound (sorry) all that dirty, but is, in fact, a pretty advanced form of sexual play. With high risk of infection, injury, and potential trauma, it’s certainly up there.

So, what is sounding, exactly?

Also called “cock-stuffing,” “urethral sounding,” or sometimes “catheter fetish,” sounding falls under the larger umbrella of “medical play,” and involves inserting a sound (a long, thin rod, often made of surgical steel) into the urethral opening (the pee-hole) and down toward the bladder (the pee storer? Pee closet!). So, to clarify, the urethra is the canal that transports pee or semen out of the body, and “sounding” is sticking a tiny metal rod (or something else, if you're adventurous) into it. Got it?

In a medical (that is, non-kinky) context, the purpose of a sound (also spelled sonde) is to gently probe, unblock, or expand a passage inside the human body, most commonly a urethra or uterus. In a sexual context, sounding can provide heightened sensation and pleasure, (more on that to come), and can also be used for control or humiliation in a domination/submission situation. Not coincidentally, if you Google “sounding”—don’t do it, dad—one of the top results involves whales. This is because sounding (in a fetish sense and a science sense) means “to find the depth” of something, such as measuring a body of water. Whale sounding, then, is what it’s called when whales dive to great depths. (#TheMoreYouKnow)

It’s more common for people with penises to partake in sounding, though people with vaginas also engage in the practice. The implements for vaginas and penises differ because vaginas have much shorter, differently shaped urethras.

Sounds (which are also sometimes called “bougies”) can technically be anything that’s slender and that you want to put in your urethra—forums on sounding have mentioned everything from thermometers to knitting needles to army beads to silicone-based toys. Though the classic (if one can call it that) surgical-grade steel sound is the one that’s most recommended, because stainless steel is easier to sterilize and, you know, won’t cut you, break, or leak mercury into your body the way a glass thermometer might.

Sounds commonly come in two shapes, according to the Deviant’s Dictionary: Van Burens (which are curved) and Dittels (which are straight). There are also medical devices that can expand one’s urethra (also called dilation), which are named Pratts or Hegars, but these are also usually referred to as sounds, as well.

But why do people like to stick things in their urethras?

People engage in sounding for the same reason they engage in anything: Because they enjoy it. And they enjoy it because it feels good.

As Simon, a sounder I spoke to who wished to remain anonymous, put it, “It’s not that it’s pleasurable in the same way that, say, a hand job is pleasurable. It’s an intense feeling, and one I didn’t initially think I would enjoy. But once the sound goes all the way in, to where my prostate is, then it starts to be more pleasurable in the traditional sense.”

The stimulation of the prostate (or p-spot) through the act of sounding is often listed as one of sounding’s main benefits. Indeed, the route of the urethra crosses right through the prostate gland on its way to or from the bladder. This region even has a name—the prostatic urethra. The taboo of penetration, especially of a part that is not commonly penetrated, is also a kinky perk for some, as well as heightened orgasm during sexual activities (masturbation, slowly moving the sound in and out, hand jobs, blow jobs, etc.), overall intensity of the experience, and the accompanying sense of vulnerability. That was the main draw for Rita, Simon’s girlfriend, who initially proposed sounding to him. “For me, one of the hottest things is to see a man be truly vulnerable, and sounding is great for that,” she said.

In a BDSM context, sounding can be a form of power play. Curved sounds, which we now know are called Van Burens, after president Martin Van Buren, jkjk... They were named after William H. Van Buren, an American surgeon who brought a great deal of respectability to the field of urology in the 1800s, despite writing books called Lectures on Diseases of the Rectum. (He also was the first person to determine the average length of a male urethra—22.3 cm, or around eight inches, if you must know.) Because they are curved, if a Van Buren is inserted all the way in, a dominant can ostensibly control if/when a submissive gets an erection. If they do get an erection, it can be painful, which might very well be the point.

How large are sounding rods?

According to MedicalToys.com—which offers a detailed breakdown of how to sound, how to clean your sounds, and of course, where to buy sounds (from them!)—the diameter of sounds, catheters, and a few other medical instruments is expressed in the “French system.” One French unit (Fr) = .33 millimeters. So, for example, a 20 Fr sound = 20 x .33, which is about 6 mm in diameter, or a quarter of an inch. The larger the sound, the more intense the experience. The site also notes that “Most men can, without discomfort, take a much larger sound than you might imagine. That being said however, for first timers, or those who haven't done it on a regular basis, start out with the smaller sound diameters (i.e., 10 Fr or 14 Fr) and work up to the larger diameters.”

What are the safety risks of sounding?

The urethra, like many of our internal parts, is made up of delicate tissue, and injuring it by way of tearing or cutting can lead to a UTI (urinary tract infection). That’s why it’s important to use sterile, smooth, shatter-proof sounds. Navigating the curve in the urethra near the bladder is also risky because there’s a chance you might puncture it. And that’s just as horrid as it, well, sounds. Additionally, some pain or discomfort may be felt when dilating a urethra, as it is stretching the canal beyond what most people are used to. If sounders continue to experience pain, irritation, or bleeding, however, they should, of course, visit a doctor. And also tell the truth about what happened.

As a friend of mine told me who tried butt-chugging waaaay before butt-chugging was a thing and ended up in the ER, urologists and proctologists have heard everything. And the only way they can help you is if you tell them everything, too. So, quelch your embarrassment and be honest. They might even offer you tips to avoid further infection or damage.