Robots that move to music have become popular holiday decorations.
The Hip-Swinging Monster and other dancing figures are popular holiday novelties or gag gifts. You've probably seen many of the different versions at a store in the mall, at the flea market or on television. You activate them by doing one of three things:

  • Making noise
  • Moving in front of them
  • Pressing a button
When activated, the figure begins moving in time to a popular tune that comes from the base of the figure. Instead of having built-in music, some versions actually dance to the music from your own CD player or radio!

Click here to see a short video of the monster dancing.

In this edition of How Stuff Works, we will open up the monster and take a look inside. What makes the music? How does he move? How do his eyes light up? We will answer all of these questions as we take a look inside.