A spin-off from the more commonly known act "drunk dialing" this occurs when a person is intoxicated, logs on to his facebook account and makes an unusually high number of comments, not limited to exes (ex-girlfriends or ex-boyfriends, whatever the case may be) but to his entire facebook friends list and sometimes his friends' facebook friends lists as well (depending on the level of intoxication). Emboldened by alcohol, he thinks every comment he's making is funnier than the last one he just made and won't stop until he experiences actual passing out (sometimes occurring mid-commenting and on his keyboard).
(See also Facebook Walk of Shame, Facebook Hangover)
John: Why did Bob grab my case of PBR and close the door to his bedroom?
Mary: He's drunk facebooking tonight because he hasn't talked to his parents and friends back home in such a long time. Tomorrow his profile picture will be of a unicorn humping a hippopotamus and his status update will be a blanket apology to those he may have offended as he nurses that inevitable facebook hangover.