Birthdays are the days the people around you came into existance. So it's highly important for you to remember your family members' and your friends' birthdays.
If you already know all of them, congrats!
If you don't, then... guilt will always be on your shoulder. Sitting there. And when it's your sister's birthday, or your best friend's, it'll poke your neck. And that sensation will travel all the way down to your heart and stay there for about a day. Maybe 2 (1 week is the highest).
There's all kinds of ways you can figure out birthday dates.
1) Ask a fellow friend/family member
2) Close your eyes, dig into that memory bowl of yours,
and search for it
3) Check out a website profile of theirs (FB, Myspace, etc.)
4) Ask them
I suggest #1 and #3. In #2, you might hurt yourself. And #4... I just put that out there. You can do that. I'm sure it'll save time but I don't recommend it. It seems, I dunno, rude? If you ask, you might get that, "You don't know my birthday?!" look. Complete with a surprised expression, raised eyebrows, and in rare occassions, a glare.
And you don't want that.
It's also a huge boost for them when you say, "Happy Birthday!" Because, hey, someone knows the date you were born on and it shows that they love you for being born. (I'm almost positive saying "Happy Birthday!" is a solution to depression, too, 'cuz it has that much power to make anyone happy)
Seriously,
Wicked