Heh, the only person's birthday I remember definitely (other than my own) is my sister's. My mom's I almost have - but I consistently think it's either a day earlier or later than it actually is. But I'm super close. My dad's - I know the month! And I'm pretty sure it's in the middle, somewhere! And one of my best friend's, I remember his. Little confused on the exact day but I think I know it.
But everyone else? Yeahhh... not so much.