There was a fun recent AP article about presidential doodling! Apparently, Herbert Hoover was quite the doodler, but most of the Presidents doodled in some form.
From the article:
Personalities emerge at a glance: John Adams' hard, straight lines and precise geometrical patterns; Theodore Roosevelt's rugged sketch of two dogs staring across a campfire; Dwight Eisenhower's plain, practical illustrations; Ronald Reagan's childlike portraits, including of himself in a cowboy hat.
So take some time to read about doodles (you wanted to have some fun this afternoon, I know it!).