In Debian and Ubuntu, you can install it using:
# apt-get install nyancat
The options I used mean:
-n, --no-counter
Do not display the timer.
-s, --no-title
Do not set the titlebar text.
-f, --frames
Display the requested number of frames, then quit.
44 frames equates to about 4 seconds, which is the same amount of time it takes my machine to run sl.