Have you ever done that this: It's a little after midnight. You're on Facebook. You check the list of upcoming birthdays and see that one of your friends has a birthday coming up. You go to wish them a happy birthday, then notice that no one else has wished them a happy birthday yet. So you hold off, because you're not good enough friends that it's acceptable for you to be the first person to wish them a happy birthday. You promise yourself you'll come back in like 12 hours and wish them a happy birthday, but then you forget. And you feel mildly guilty.
You know you have.