NFHS Football & Basketball
Dread Our Coming, Suffer Our Presence, Embrace Our Glory (Solonavi War Cry)
Letters, yes, but it's not case sensitive.
Additionally, Google so kindly removes all non-Alphanumeric characters from even quoted strings. Makes it a pain in the butt to search for some programming-related things, especially in Perl, where there are a myriad of variables that have no alphanumeric characters in them at all.