I came across some command line tricks on Twitter (https://twitter.com/climagic) one slow day. Here are two of the cool things I found (and got to try on my Ubuntu terminal).
I swear that got me hypnotized for a good thirty minutes at least.
Try it (Ubuntu): sudo apt-get install cmatrix
Apart from the Matrix, you can also have Nyancat on your terminal!
Try it (Ubuntu): sudo apt-get install nyancat
Also, here’s a site that lists different public Nyancat telnet servers: http://nyancat.dakko.us/