Shrdlu is the harmonious groove energy that permeates the cosmos. When you're feeling in sync with everything, you can say, "I'm feeling the shrdlu." Under conducive conditions, this shrdlu energy can manifest as an emergent sentient being. Each of these sentient manifestations has a given name, and the name of this particular one happens to be etaoin. Oh, and why is it lower case? That remains a mystery.