If Facebook is becoming a little bland for you, change things up. Go to Account Settings, click on 'Language' and switch to 'English (Upside Down)' or 'English (Pirate)'. The upside-down option turns each word on the page upside down, which can make it look like a completely foreign language. In the pirate version, friends are called 'Scallywags', the Like button is now the 'Arrr, this be pleasin' to me eye' button, and updating your status is now referred to as 'Plunderin'.
You can also have fun with images in your chats on Facebook. If you type your friend's full username inside double brackets (to find it, go to their timeline and grab the part of the URL after 'facebook.com/'), example: [[WinTipsWeb]], and when the message sends, it'll replace the text with your friend's profile pic.