My birthday comes on christmas Lyrics

I got a drum. I got a horn
They gave me a bicycle just for being born
But I'm only getting half of what I oughta
'Cause my birthday comes on Christmas

I got a train, it really runs
They gave me a space suit, it should be lots of fun
But I'm only getting half of what I oughta
'Cause my birthday comes on Christmas

Gee but it's tough to be a kid like me
But I guess there is nothing I can do
'Cause all of the stuff beneath the Christmas treeAdam Brand - My birthday comes on christmas - http://motolyrics.com/adam-brand/my-birthday-comes-on-christmas-lyrics.html
Has to count for my birthday, too

I get so mad at Mum and Dad
Of all the days that they picked to have me had
And they only give me half of that they oughta
'Cause my birthday comes on Christmas

I get so mad at Mum and Dad
Of all the days that they picked to have me had
And they only give me half of that they oughta
'Cause my birthday comes at Christmas

Why does my birthday have to come on Christmas?