My girlfriend used to change her birthday every month or two, to see who would send her birthday wishes repeatedly -- she believed that people shouldn't rely on Facebook for such information. I finally convinced her to stop after I got sick of seeing the same 50 people write on her wall every month. Luckily I was in on this and put her birthday into Google Calendar...

My brother entered a false day intentionally thinking that it would be it would be a good way to filter genuine from empty happy birthday wishes.

My brother updated his birthday to the 9th of the current month for 8-9 months straight and got birthday wishes every month. He carefully monitored for and deleted people giving it away on his wall, and reading the posts (often the same people for several months) was hilarious. 'hey man, I totally thought your birthday was in May? oh well, happy birthday!'

I deleted facebook 3 years ago, so I actually get real live phone calls from people who actually know. =pp

Surely most of us have an extraordinary number of friends who were born on January 1...