Today is my thirtieth wedding anniversary! Lots of well-wishes have been coming our way on FaceBook and in person--and I am in quite the celebratory mood! :)
Of course, any written words spark interesting discussions about grammar and usage (in my head at least!). And with my anniversary today and my birthday tomorrow, these greetings warrant a little "language lady" attention!
Obviously, happy, birthday, and anniversary are not proper nouns in themselves. However, when you write these as greetings, they should be capitalized.
Thus, you would capitalize
Happy 39th Birthday! (LOL!)
Happy 30th Anniversary!
However, you would not capitalize these same words within a sentence when describing a birthday or anniversary: I had a happy anniversary. I enjoyed by day and had a happy birthday.
So...Happy Anniversary and Happy Birthday to me! :) and Happy Flag Day (tomorrow!) to you!