...And proud of it!
Have you ever heard of Gnu/Linux operating system? If not, it is is a Unix-like computer operating system assembled under the model of free and open source software development and distribution.
In short, an operating system which is free as freedom, where you can tweak it to something that very personal, and free as a free beer, well, most of it.
Ah, and yes, the mascot of the kernel, the brain of an operating system is Tux, the Penguin.