Doodles we'd draw in math classes or when working on projects. Or when you're trying to describe something to someone by making a quick sketch, really rough sketches with stickman figures doing stuff. Were they a thing back then? Were they common? What kind were they? Did they have rough sketches or were they a lot more detailed?
From the thread I linked:
I tend to think of them a little bit like the cartoons and random drawings in the New Yorker--little illuminations that don't illustrate the text. There's a couple decades in the 1300s, for example, where adding strawberries to borders suddenly became A Thing--and then it stopped.