So many people believe there is no harm in engaging in a little bit of gossip, however, this is a very naive assumption, as any gossip you personally share drags you down to the level of the situation - even if only temporarily. "Why?" you ask. Anytime you gossip about another human-being, you have to put yourself (your mind) through a negative experience. The act of gossiping requires you to go through a process of a) recalling the situation or story in order to tell it, and b) verbalizing it to whomever you're going to gossip with - hence, you have to (mentally) experience it. And, while this may sound like a benign activity, when you do this your mind can not tell the difference between the "story," you're telling, and the things you desire.
The function of our mind, besides making sure that all of our internal parts are working in proper condition, is to help us decipher what experiences we desire. Additionally, the mind is programmed to seek out those things we want, and the way that it deciphers our wants and desires is by what we give our attention to. For example... have you ever noticed that when you want a new car, you begin to see all the other cars that are like it on the road? This occurs because your mind will only seek what you tell it to.
How does this relate to gossiping?
When you gossip, you are giving your undivided attention to the experiences of the story... and, just like it is with the new car, your mind believes that you're focusing on it because you want to experience something that will bring up those same (negative) feelings. Hence, it will begin to seek all the ideas available to you to duplicate the experience.
This is why, no matter how trivial it is... you should make a practice of never gossiping... not only because you'll develop a "bad reputation," for engaging in the behavior but, because it hurts you too!