Skype has been feeling under the weather lately. The Microsoft owned VoIP/messaging service has been affected by a pretty nasty big recently. The bug will send your messages to random contacts, sometimes whole conversations. If you like to gossip about others you can see why this is a problem.
Skype has confirmed the big exists, and is working on a fix as we speak. A Skype employee says “We are currently investigating and hope to provide a solution for this soon.” A fix for the issue should be available in the next few days. Until then try to keep the gossip down to a minimum.