I use Ubuntu at work. Instead of typing ls (list directory - similar to dir on Windows), I typed sl today. I got a message saying sl was not installed and that I can installed it using apt-get install sl.

Did that. Entered sl.

And, I saw a train chugging across my screen! See screenshot.

What accidental fun!!! It is great to have this ubuntu feature that lets you know which package to install to run a particular command (in case it is not installed).

p.s. Package description for ls is -
Correct you if you type `sl' by mistake
Sl is a program that can display animations aimed to correct you if you type 'sl' by mistake.
SL stands for Steam Locomotive.