"fb- is the father" was a meme in the early days of Fark. A user going by the handle "fb-" submitted an article discussing the birth of a child to celebrity Liz Hurley, appending "fb- is the father" to the end of his headline. The meme quickly spread, often showing up in headlines for articles on other famous births, births of certain types of baby animals, and so forth.
In the mid-2000s, the user "fb-" was banned. The string "fb- is the father" was eventually added to the Fark filter, so that the phrase would be automatically eliminated from any submission. Evidence of the phrase can be seen via Google searches, and some threads that mention it remain in the archives (example ).
"fb- is the father" did not appear in a headline on Fark again until June 22, 2011 in thread 6318196 (thread ). The most recent appearance was on March 4, 2014 in thread 8165155 (thread ), "Scarlett Johanson expecting her first child. fb- is the father".
The next most recent apparence referencing fb, happened on 25 April 2017, "Barbie's got a bun in the oven. Ken demands paternity test. fb- quietly skulks away." (http://www.fark.com/comments/9565839/Barbies-got-a-bun-in-oven-Ken-demands-paternity-test-fb-quietly-skulks-away#new)