Posting "Happy Birthday" messages, pictures, and videos on a friend's social networking site when it is not his or her birthday. The joke annoys the person who receives the messages and confuses his or her friends. Also, this is an excellent way to separate one's friends from mere acquaintences since true friends will know one's actual birthday.

If the birthday bomb generates mass confusion or is especially entertaining, it becomes an Epic Birthday Bomb.
Wait. Is it really your birthday? Or, is this a birthday bomb? I thought we just had a party for you like two months ago.

Josh totally birthday bombed me. It was so annoying! My phone kept ringing all day with notifications.

Let's birthday bomb Christine! We still need to get her back for making us watch American Idol with her.
by vonchillyfries June 29, 2010
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Epic Birthday Bomb is when you, and possibly a few friends, start leaving fake birthday wished on someone's social networking profile in hopes that others will unknowingly follow along.

This acts as A) An annoyance for the person receiving numerous status updates when it's not even their birthday, and B) A nice way to past time at your otherwise boring ass job.
Dave B: Did you see how many idiots thought it was really Rob's Birthday when all they had to do was look on the information section?

Jeannette B: TOTES! Epic Birthday Bomb!
by Todd N'Erection June 26, 2010
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When you wish Happy Birthday to someone by copying what someone else (who you don't know) has posted on your friends wall. Ideally, this will be some inside joke that you know nothing about, be slightly personal and a little bit weird.
Facebook Birthday Bombing is doing this to a girl/boy you kind of know, don't really know what she's up to and don't intend to see anytime soon...

"Happy Birthday Babes!!! WONDERFUL to see you last week, hopefully this weekend at Ollie's will be megabants!!! xoxoxoxox P.s. Ibiza 2k8. Always remember it!!"
by The Banter Bus October 31, 2011
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