For that brief moment, you know more than the other. The satisfaction that you feel is of the ego, and it is derived from feeling a stronger sense of self relative to the other person. Even if he or she is the president or the pope, you feel superior in that moment because you know more. Many people are addicted to gossiping partly for this reason. In addition, gossiping often carries an element of malicious criticism and judgment of others, and so it also strengthens the ego through the implied but imagined moral superiority that is there whenever you apply a negative judgment to anyone.
