Here's our setup - a large speaker that we didn't mind ruining. It's connected to an amplifier, which we also didn't mind ruining - though we didn't end up ruining it.
We used Nate's laptop as a tone generator running the trial software NCH Tone Generator, giving out a 60Hz sine wave. We found that frequency had little bearing on the effect - volume was what really mattered. This was nice because we could set the frequency to 60.1Hz and our HD camera shutter speed fairly high to give the bouncing effect in the video.
To begin with, the effect was not very pronounced. We made a few mistakes here - we had elevated the container from the speaker, and only attached it with tape, causing most of the vibration power to be lost. Later we just put plastic wrap on the speaker itself, allowing all of the energy to be transferred.
We then experimented with various viscosities - this is very diluted, mostly water. Jesse played a prank on Brenda which you can see in the source footage - he told her to look closely at the waves and then he blasted the volume, spraying her with starchy goo!
Of course, why should we stop there? We had another fun dye, Fluorescein, hanging about. You'll remember it from Nate's Time Fountain (it also turns your pee fluorescent). A flick of the cap again turns the vibrating goo into a techno-rave monster!