I didn't post the days to my boss's calendar when we first started working together, it just felt awkward like I was saying "Reminder: Buy me a gift".  Then we talked about it and he felt awful when he missed my birthday, he told me to put the dates on his calendar because he has so much going on, that if something isn't on his calendar then it doesn't exist. For Admin Day he usually sends flowers (or, should I say, his wife sends flowers), birthday is a gift card.  Christmas is when we exchange bigger gifts.