It's super easy to create your own cows. Just look at any of the files in /usr/share/cowsay. You basically just have to get an ascii picture and add a couple of tags. Mine's a hypnotoad.
He already had the cow art file on his computer for some reason so I think the deed took him only a minute or so. The overall effect was that if you entered a command not recognised by the shell (like typoing dc instead of cd for example) an ascii-art version of a certain microsoft paperclip would respond "I'm sorry I don't know how to dc, would you like help with that?"