This is what happens when you run water through a sine wave. What you’re about to see is a stream of water bending like a sine wave when exposed to a powered speaker with the frequency set to 24hz. As Brusspup explains, this effect cannot be seen by the naked eye, but only through a camera that shoots 24 fps like in the video below.
But the magic doesn’t end here. By setting the frequency to 25hz, the water will look like it’s moving forward, and at 23hz, it’ll look like it’s going backwards! Prepare to have your mind bent here.