When one realizes that his/her own birthday is coming up, usually within about 30 days, which leads them to post happy birthday messages on their friends' Facebook walls whose birthdays fall within said 30 days.

The idea behind this is to seem nice and boost their positive karma so when their birthday comes around, they receive more birthday wishes posted on their wall on Facebook.
Steve, quit trying to boost your Birthday Karma by posting birthday wishes on your friends' walls. We all know you're not being sincere about it.
by subatomicpotato July 15, 2010
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