JMcAndrew asks, “Why would anyone staying at a hotel pay to hear adulterous noises?”
All I can think is that this is leaning into that particular trope of cheap motels. Anyone who has ever experienced such might appreciate a line that I wish I’d written:
“For the first 20 minutes it was funny; then it was irritating; then it was actually pretty impressive…”
OK, that might warrant an Arlo tag…
Comics I Don't Understand 
Ever notice how sometimes you can’t sleep because of the noise… and sometimes you can’t sleep because of the silence?
Maybe patrons of this motel are so used to those sounds that they need artificial noise to help them sleep?
I agree with Powers. If the ambient noise is not JUST right, can’t sleep
I had two different thoughts upon seeing this one, neither quite making it as a joke:
1) the gizmo is just covering a hole in the wall into the adjacent room; put in a quarter it will remove a soundproof barrier, allowing you to hear into the next room, where, being it’s a cheap motel, obviously you’ll hear adulterous sounds.
2) if you’ve come to this motel just to sleep — how embarrassing for you! — you can put a quarter into this machine so it will make adulterous noises to cover for you, so you can keep your street cred.
Oops, inflation! Two quarters!
I like Lark’s idea of generating the sounds to create street cred with your neighbors.
I know it’s not, but the style and the setup both made it feel like a “Kliban” to me.
Without getting into the particulars, it felt funny to me just as a stupid riff on the “massaging fingers” contraptions. (I feel like they lifted the image for those things from a horror dime novel).
And while I guess that should be a suitcase, it just looks more like a ridiculously oversized briefcase.