Why do I sometimes shock myself when I kiss Uncle Al? — BS
If both of you were electrically neutral before the kiss, nothing would happen. Evidently, one of you has developed a net charge and that charge is suddenly spreading itself out onto the other person during the kiss. That charge flow is an electric current and you feel currents flowing through your body as a shock.
Most likely, one of you has been in contact with a insulating surface that has exchanged charge with you. For example, if you walked across wool carpeting in rubber-soled shoes, that carpeting has probably transferred some of its electrons to your shoes and your shoes have then spread those electrons out onto you. Rubber binds electrons more tightly than wool and so your shoes tend to steal a few of electrons from wool whenever it gets a chance. If you walk around a bit or scuff your feet, you’ll typically end up with quite a large number of stolen electrons on your body. When you then go and kiss Uncle Al, about half of those electrons spread suddenly onto him and that current flow is shocking!