The eXtensible Messaging and Presence Protocol, XMPP, has extensibility at its core. It is because of the extensibility that there is a vivid XMPP ecosystem: it is easy to adapt XMPP to new developments and to new use cases. The XMPP Standards Foundation maintains a list of extensions to XMPP. In this talk I will dive into this list of extensions: what kind of extensions are there? What statuses can an extension have? What extensions to use in some common use cases? And I will touch some exotic extensions for use cases you may never have thought about. Oh, and what is the story about these ‘humorous’ extensions, can a protocol be humorous?