Cowsay is a command that can be used to make a graphical dialog.

@cowsay Hello, World
< Hello, World >
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

Cowsay also has an extra argument to add some variation:

@cowsay /list
cowsay <message>
cowsay /<style> <message>
cowsay /<cow> <message>
cowsay /<cow> /<style> <message>

cow styles:
 /borg /dead /greedy /paranoid /stoned /tired /wired /young /think /joke

cows: (e.g. cowsay /beavis)
  beavis           bong             budfrogs         bunny          
  cheese           cow              cower            daemon         
  dragon           dragonandcow     elephant         elephantinsnake
  eyes             flamingsheep     ghostbusters     headin         
  hellokitty       kiss             kitty            koala          
  kosh             lukekoala        meow             milk           
  moofasa          moose            mutilated        ren            
  satanic          sheep            skeleton         stegosaurus    
  stimpy           supermilker      surgery          telebears      
  turkey           turtle           tux              vader          
  vaderkoala       www