Custom php code output to footer

[Defkalion]

I have a piece of code that depending on the page url will display a different word at the footer. How can I include this in my footer? I probably should add this code to a plugin and then just throw the final variable that comes at the 'echo' part of the code end to my footer template. Is this correct? If yes, in which hook location should I create this plugin? If no, well, any other ideas?