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.