Source : Free On-Line Dictionary of Computing

BUAF
     
        [alt.fan.warlord] Big Ugly ASCII Font.  A special form of
        {ASCII art}.  Various programs exist for rendering text
        strings into block, {bloob}, and pseudo-script fonts in cells
        between four and six character cells on a side; this is
        smaller than the letters generated by older {banner} programs.
        These are sometimes used to render one's name in a {sig
        block}, and are critically referred to as "BUAF"s.  See
        {warlording}.
     
        [{Jargon File}]