Christmas Eve or Day?

Living in the USA I am eternally confused.

For example, right now it's 5:30am on Christmas Day in Australia, but here in the USA it's 1pm Christmas Eve. Because it's not at all related to when you were born, Christmas Day always falls on the 25th day of December of the timezone you are currently in, no matter what. So even though it's Christmas Day in Australia, I am celebrating Christmas Eve.

However, your birthday is relative to the timezone in which you are born, or is it? Come late afternoon on June 10th in the USA, is it really my birthday because in Australia it will already be June 11th? But then what happens to all the hours that you lose then gain while you are travelling? Do they ever even out or do you rack up a deficit, or surplus, somewhere? Does this affect when your birthday really is? Could my birthday really fall on June 12th by now? Don't get me started on leap years...

Anyway, back to Christmas. I wonder if my Dad will let me open a present tonight, even if it's just Christmas Eve for us?

I can't wait to call them and wish them a Merry Christmas. Although I used to wake my parents up at 3am to open presents, I don't think they will appreciate a 5:30am phone call today!

So I have to wait for a few more hours, then use the wonderful modern technology of Skype to see them.

I wonder how bad Kate and Tim's hangover will be after their big day out for Christmas Eve?