:) Hello there @pixiehunter. As mentioned in the experiment, when two materials are rubbed together, especially insulators, some electrons leave one of the material and enters the other one, leaving the first material with a net positive charge and the second material with a net negative charge. If, for instance, your bare feet were one of those materials and the rug in your living room was the other material, shuffling across the floor would give your feet or your body that net charge. So when you grab the door knob on a dry day, there would be a transfer of charges from your body to the door knob, giving you a little shock. Thanks for visiting my blog. You're appreciated.