Cowsay is a Linux tool drawing a cow with a bubble into your terminal.
To have more fun starting your bash you can add it into your bash configuration in Debian:
$ sudo apt-get install cowsay fortune
Next edit your
~/.bashrc file and add the following script at the end of this config file:
if [ -x /usr/games/cowsay -a -x /usr/games/fortune ]; then fortune | cowsay fi