Most often when a male encounters a female and gets the facebook add. The newly met female posts something flirty and is quickly met with a post right above by a girlfriend or the girlfriend's friend.
This is intended to let the male know that she read this new girl's post and does not approve of it.
NOTE: To prevent facebook cockblocks send private messages in the future.
Matt's facebook wall:
GF's post: Heyy babe, just wanted to say i love you so much! (translation: dont you fucking respond to that post below or i will rip off your nuts)
Shirley's post: hey matt, i had a great time last night with you! give me a call sometime :)
(later)
Matt: Yeah i met this hot chick last night at the concert, but lauren facebook cockblocked me when she wrote on my wall
20👍 10👎