As my toddler had me up at the wee hours one recent morning, and we were due to attend our first birthday party of his best buddy at daycare, the following occurred to me about the term "birthday."
On the anniversary of people's birth we call that their "birthday," but generally I don't hear people refer to it as the day they were "birthed"; it's the day they were born. Giving birth is more what their mother did (and probably for many hours prior to the actual emergence out into the world which is considered the moment of birth, as though all that traveling through the birth canal up to that point was unimportant).
So conceivably the expression instead should be "Happy Born Day," with "Happy Birthday" being what you would direct toward the person who actually did the birthing.
This is why I shouldn't think at such an hour.
On the anniversary of people's birth we call that their "birthday," but generally I don't hear people refer to it as the day they were "birthed"; it's the day they were born. Giving birth is more what their mother did (and probably for many hours prior to the actual emergence out into the world which is considered the moment of birth, as though all that traveling through the birth canal up to that point was unimportant).
So conceivably the expression instead should be "Happy Born Day," with "Happy Birthday" being what you would direct toward the person who actually did the birthing.
This is why I shouldn't think at such an hour.