Oh my. There I am expounding on ellipses on the overhead and switching pens to make various components of the ellipse stand out, when a big blob of red blood-looking stuff plops out of the pen and onto the slide. Ew. Toss the pen. Continue talk. Expound expound expound. Another red pen. Another big plop of red oozes from the seams of the red pen. Another toss.
This has happened before. And only with the red pens. What's the deal? ... And another thing. Wouldn't it be nice to buy colors individually or to mix and match to make your own set: purple, black, brown, dark green, darker red (bloodless), blue, fuschia, ...
Did I mention that we looked up the phrase "vis-a-vis" one time in class and it means "face-to-face"? How appropriate.
Footnote: when I looked at my piling up slides later, the red blob was transformed into a Rorschach test sample.