Powny is what a Yamaha PSR-215 became after few joyful games with solder and connectors.
The goal was to make the central “sound chip” misbehave in a modular way. So, each leg of the chip was connected to a small “banana” connector. And, as you guessed, the user can connect different legs together, making the chip malfunction in an 8bit crazy way. The results are sometimes really stunning!
Here, you can get a taste for yourself…. a mash-up of normal vs. bended Powny singing: