The Jargon File (version 4.4.7, 29 Dec 2003):

bixie
 /bik'see/, n.

    Variant emoticons used BIX (the BIX Information eXchange); the term
    survived the demise of BIX itself. The most common (smiley) bixie is
    <@_@>, representing two cartoon eyes and a mouth. These were originally
    invented in an SF fanzine called APA-L and imported to BIX by one of the
    earliest users.


The Free On-line Dictionary of Computing (30 December 2018):

bixie

   /bik'see/ Variant emoticons used on Byte Information
   eXchange.  The smiley bixie is <@_@>, apparently intending
   to represent two cartoon eyes and a mouth.  A few others have
   been reported.

   [Jargon File]

   (1994-11-29)