"Well, that explanation was shorter than usual. It's Billy! Who's Billy?"
Giles's frustration at being unable to read are funny and interesting to watch, but problematic because it's based on a pretty superficial understanding of Giles as a character. Slightly more effective is the moment where he sees Buffy's grave, and realizes that this is his greatest fear--now we're seeing him as something more than a caricature-ish academic figure.