When Penny locks herself out of the apartment, she comes to hang out with Sheldon in his as he plays Age of Conan. Penny, frustrated by her recent failures in life soon plays and becomes addicted to Conan.
Sheldon: I'm a physicist. I have a working knowledge of the entire universe and everything it contains Penny: Who's Radiohead? Sheldon [after twitching for a minute]: I have a working knowledge of the important things