Social capital is anything that enhances your social standing. If you were with a group of professional musicians, a deep knowledge of Mozart would be an example of social capital, because that knowledge would be valued by that particular group. If you were with a group of people who had no jobs and were homeless and desperate, your father the janitor would be pretty impressive. Social capital is a relative term, depending on what group you're in at the time. You can choose to spend your social capital when you choose to reveal your special knowledge, talent or status.