My understanding is that for it to be a 'proper' happy birthday i.e. "happ-ee-ee birthd-ay-ay-ay-ee to INSERT NAME - happ-ee-ee birthd-ay-ay-ay-ee to y-ee-ooo-ooo-oooo". Brithdays require individualisation (or is that individuation or is that just the Jungians?) to be truly happy. I think its about being glad that the individual is born and letting them know - otherwise its too general. Having said this, I have conducted no academic research on the matter but would venture to say if every day is a birthday, which is a reasonable statement, then every day is also a death day, a divorce day, a winning some money from somewhere day, a no job day, a wonderful job day, and so on and so on. How long can we make this list? So ......... in GENERAL terms every day is something, in specific terms we require an individual to make it INDIVIDUAL if that makes sense! Go the individualists I say! (Just a bit of a rave folks, to amuse myself.)