Use clippy for shell errors.

.bashrc

function command_not_found_handle {
	{echo "It looks like you're trying to run a UNIX command.";echo "Would you like some help with that?"; echo; /usr/lib/command-not-found $1 2>&1|fold -sw 55}|cowsay -f$HOME/.clippy -n
}

.clippy

##
## Good old clippy
##
$the_cow = <<"EOC";
   $thoughts     ___
    $thoughts   /   \\
     $thoughts /     \\
      /       \\
    ___       ___
   /___\\     /___\\
   \\*__/     \\*__/
     |        |
     | |      | |
     | |      | |
     | |      | |
     |  \\    /  |
     |   \\__/   |
      \\        /
       \\      /
        \\____/
EOC

.zshrc

function command_not_found_handler {
	{echo "It looks like you're trying to run a UNIX command.";echo "Would you like some help with that?"; echo; /usr/lib/command-not-found $1 2>&1|fold -sw 55}|cowsay -f$HOME/.clippy -n
}