I liked dragging a selection box on the desktop and seeing how thin of a line I could turn it into. When it was perfect the line would dissapear and just have one pixel on the top and bottom. It was also fun to draw the smallest possible box around random things on the desktop wallpaper. I did that with the windows 7 stock wallpaper a lot.
https://youtu.be/LoYP2mEJDJs?si=WQdZBTmWOyGcvhNJ