Though officially called "William Shatner's Birthday" Day, most people abbreviate the name to Shatner Day. The traditional greeting is "You're looking Shatnerrific!" or "Have a Shatner-tastic Day, Comrade."
As of today Canada officially adopted Shatner's new and improved and FABULOUS lyrics to our national anthem. "O Canada" is seldom played or performed other than at hockey games or public school assemblies, because Canadians are pretty lazy when it comes to patriotism. Which is too bad, because I think the new version is Shatnerful:
Happy 81st Birthday, Comrade Shatner!