DuckCorp Dico

Found one definition

1.                 From The Jargon File (version 4.4.7, 29 Dec 2003):
                   
   
   
                   
                     
   AFJ
    //, n.
       Written-only abbreviation for “April Fool's Joke”. Elaborate April Fool's
       hoaxes are a long-established tradition on Usenet and Internet; see 
    kremvax for an example. In fact, April Fool's Day is the only seasonal
       holiday consistently marked by customary observances on Internet and other
       hacker networks.