Several of my university students keep sending me to this web site, saying "read this one...." So, I share it with you.
CircleVersusSquare is a web comic produced by Michael Wakcher. He also writes a non-math webcomic and maintains Wakcher.com, his personal library of original quotes and witticisms.
The web comic is the story about Circle and Square, two geometrical shapes who hate each other. The full 216 episodes document what Wakcher describes as their "battle in a never-ending game of one-upsmanship."
Other characters appear: Triangle, Pentagon, Diamond, Rectangle, Parallelogram, and Heart. Read the "About" section, so you have some idea of the character's character...
Though I could suggest you browse several favorite panels (e.g. 48 or 175-178), it is best that you start with Episode 1...and follow the story (i.e. battle) as it develops (i.e. escalates). This way you will see how the new characters enter the scene as well.
Browse the "Forum" section as well. It contains some interesting commentary...perhaps traceable back to either a love or hate for mathematics. It is surrpising to see the emotions provoked by these geometric shapes.
Finally, click on the link "Letters From Mr. Z." It is great...as Mr. Z is some person (e.g. mathematician) who took "umbrage" with the web comic, threatened legal action, and insisted that Wakcher and his web comic "made a mockery of the mathematics community." You will enjoy this....
Unfortunately, Wakcher has ended the web comic, but I am glad it is still available on-line.
NOTE: Due to some of the potentially offensive content on this website, it is being reviewed for you as adults...and is not being recommended that you share it with your students. Though, be aware, that it quickly appears as an option when doing Google searches using terms such as "math cartoons" or "math humor."