A teacher in Thailand has many students doodling on their tests. The teacher treats this as a collaborative process and adds to the doodles. See here and here and I think the latter is the teacher's own blog.
When I found similar doodles I would typically photograph them to share but this teacher's work seems more fun.
I'm at my sister's house in Alaska so I don't feel like adding much to this post but I'll see what images I might still have.