Most people don't have a need for a group chat service all the time. While many apps require you to set up passwords and accounts, it's just not worth it for that once-a-year experience. If you need a private and secure chat room without the hassle of usernames, ChatStep is a service worth checking out.
ChatStep is incredibly easy to use. You can create a room from the home page by typing in any name you like, then your nickname and an optional password. Then, simply send your friends the room name and they can join up. When you leave, everything is deleted from the servers. Similar to the previously mention CryptoCat, ChatStep doesn't log messages, images, or user information. Better still, all your messages are encrypted before they're even sent. It's simple, but if you're looking for a quick way to chat with friend without Big Brother watching, then ChatStep is a great solution.