I was glad to learn that dry-ice can easily be purchased from local grocery stores if you're over 18, so I've made a habit of picking some up on a regular basis, and bring it home to play with my kids and show them some cool tricks. I saw a couple of neat videos on the internet showing that if you placed a quarter sideways into a block of dry ice, it would shake rapidly. I found that this only happens when the quarter is warm. So when you first put the quarter into the dry ice, and it cools down rapidly as it cuts a groove, it probably won't work. You then need to run it under some warm water to warm it back up, then set it down in the groove already formed, and it will bounce for about 30 seconds.
This shivering action happens because the dry ice that's touching the quarter rapidly warms up and turns to a gas, pushing the quarter up until the gas escapes. When the gas is out, the quarter flops back down on the dry ice and warms it up until gas pressure builds and pushes it up again. This process happens very quickly, and repeats rapidly until the quarter is too cold to warm the dry ice any further.