1. While telling your audience about an old water purification ritual you learned, drop the pushpin in the soda. The story you are telling them is called the patter. This trick is based entirely on the patter.
2. Tell them that in ancient times, the Indians didn't have filters and things like we know them. When they came to rivers or lakes that they didn't know, they would first bless the water so that all of the dangerous things would rise out.
3. Begin to chant like an Indian. Just sound mystical and mysterious as you moan. While you do this, watch the pin closely.
4. By itself the pin will start to stand up. You may think it's because you're a good Indian dancer, but really it's because the pin is so light the tiny bubbles in the soda make it float as they stick to the plastic.
5. But since your audience doesn't know this, pretend you're doing it. Gesture with your hands as if you are drawing it out magically. The pin will float all the way to the surface, where you can pull it out!