This cartoon, among my very earliest work - probably from around the year 2000 or 2001, was done when I was experimenting with different types of pens. I'd read somewhere on a website dedicated to cartooning, that a popular tool used in drawing was a Rapidograph pen by Koh-I-Noor, which I used for this, and many of my earliest cartoons. It's a great pen, but it requires consistent maintenance, or it'll stop functioning.
Below are some pictures of the Radidograph pen I used for this and others among my earliest cartoons. It's a great pen, and I'll probably revisit it for other types of art at some point in the future.
These pens, which I believe were originally created for drafting, come in a variety of line thicknesses. You can identify them by the color of the ring near the drawing tip; in this case gray, which denotes a .35 line thickness - a pretty fine point, good for a style which uses cross-hatching, as in the above cartoon.
The Rapidograph disassembled as you would to refill the ink - the clear plastic section is the reservoir. The ink capacity is limited, and you only want to use Koh-I-Noor ink both for the proper ink flow, and for the potential of it irreversibly clogging. The pen tip also breaks down further for cleaning.