Dr. S (the “S” is believed but not confirmed to stand for “Spirograph”) is a mysterious scientist who lives and stays up all night in Springfield’s Spirograph Factory. He is obsessed with Spirograph and is constantly making it, studying and researching it. He believes a conspiracy that there is a direct correlation between the decline of Spirograph and the rise of gang activity. Bart Simpson occasionally visits Dr. S and acts like he’s a casual pal of him, greeting him with “Yo, Dr. S”