When you post a fantastic status update on facebook only to have it commented on by your mother and all of her friends that unfortunately have added you on facebook. This typically prevents any of your friends from posting any funny comments and often leads to you being scolded or babied.
Carlos: yo, man i posted this awesome status and my notifications were through the roof, but then i looked at who it was from. I got mom-bombed man!
Greg: that sucks man, I hate getting mom-bombed so much that i blocked my mom from my facebook page