0220 - Lee's ass - 2021.12.20
In 1993, Sylvester Stallone starred in a little movie called Demolition Man. If you haven't seen it, it's basically Facebook-boomer-conservative propaganda in kickass action movie form - the titular hero is cryogenically frozen and wakes up in the far-flung future of 2032, where only his red-blooded common-sense American violence can save this silly ultra-liberal too-much-tolerance utopia from itself. (His name is John Spartan, for God's sake.) Much like Robocop, it really works better if you process it as a satire of action movies, though I'm not convinced that all the people involved knew which bits were satirical at the time.
Anyway, one of the enduring cultural legacies of Demolition Man is the three seashells.
In 2032, apparently, both bidets and toilet paper have been replaced with three seashell-like objects, and the joke is that John Spartan literally doesn't know how to wipe his ass. It is never explained in the film how the seashells work, but Stallone has gone on record saying that he believes you use two of them like tweezers and then use the third to scrape. I, of course, reject this explanation, both because the whole point of the scene is that he doesn't know how to use the shells, and because there is no way this method would supplant our current technology - certainly not to the point that toilet paper is no longer even provided.
Although the bathroom is never seen on screen, a prop was developed in case it would be needed, and the shells look like scallop shells. A scallop shell is a shallow dish, and dishes can be used as parabolic reflectors. Any light or EM radiation potent enough to remove poop from skin would also remove flesh from bone, so it's likely not that... what else can be parabolically reflected?
The answer, of course, is sound. Specifically, ultrasound, which is gentle enough to be used to image a fetus, and already in use to clean microcircuitry and jewelry - it's naturally antimicrobial, even! So... why three shells?
Multiple shells allow us to utilize a little something called constructive interference. Imagine two people banging drums, one striking the surface 4 times a second, the other striking it 6 times a second. Twice per second (beat #1 and #3 for the first drummer, #1 and #4 for the other) both are striking the drum at the same time, creating a louder combined sound. In the same way, two frequencies of ultra-ultrasound can be combined, so that where the beams of sound intersect, a lower, more potent frequency of ultrasound exists.
Imagine sitting on the toilet, finishing up your business. You see three little chrome scallop shells on a shelf next to you, and you pick up two of them - doesn't matter which ones. They draw their power wirelessly from the home, and you hear a faint humming, letting you know they're operational. You set them up on their flat sides, each pointing inwards towards your nethers, and a thrumming sensation begins shaking your pelvis, like your guts vibrating at a particularly loud rock concert.
You then pick up the third shell and hold it in front of you, pointed inwards. Where all three focused beams of ultrasound converge, you feel a buzzing sensation, like a gentle but determined bumblebee has gotten very, very lost. You wiggle the shell in your hands around, guiding the buzz up, around, and even in the befouled area, feeling the moisture and filth vibrate itself off of you, leaving your ass-region feeling tingly and refreshed.
The benefits of this, of course, are numerous - it consumes only power (which, in the future, is probably solar or wind-based), it's friendly for people with mobility issues, you don't ever have to reach back into the danger zone... it's easy to see how such a system would replace toilet paper!
Of course, Demolition Man is not the first sci-fi to propose sound-based hygiene. Star Trek: The Next Generation, season 1 episode 3 The Naked Now (air date: September 28, 1987) introduced the concept of the "sonic shower" (Geordi finds a woman dead in one), and sonic showers were a part of Trek continuity ever since. I will point out that TNG also introduced replicators (which can create toilet paper) and holodecks (which can simulate water), so ultrasound has replaced water and paper in that neoliberal future as well.
(It should be noted that the same constructive interference technology could also be used to turn an enemy combatant's brain into jelly, so perhaps it's for the best that this particular prophecy has yet to see widespread realization.)