It's actually a situation you may have been in before. You're in a store and you're attempting to purchase some kind of good or service ... but then you make a quick, stupid joke as part of an ill-fated attempt to make conversation with an employee and find yourself vanishing down a rabbit hole from which there is no easy escape. Sure, it probably never got as weird and extreme as it does in this 'SNL' digital short, but we all know that this is a thing that can happen.
There's only one joke here, but to the video's credit, it's also less than two minutes long. Kyle Mooney plays an employee at an ice cream parlor who doesn't quite understand why two customers would order a bunch of ice cream and "two ambulances." As the joke flies high over his head, he vanishes into his mental headspace, where he desperately searches his brain in a ridiculous attempt to understand what they were trying to say to him. Meanwhile, things only get weirder out in the real world, especially with the arrival of a co-worker played by Taran Killam.
There's no real satire here or even a clear point. This is just a single joke, executed well. And you know what? That's all you really need sometimes.