God and his son Jesus are the only characters on The Simpsons to have a full set of five digits.
Everyone else in the Simpsons universe has three fingers and a thumb on each hand, and four toes on each foot.
“When you're flicking with your remote control and a flash of yellow goes by, you'll know you're watching The Simpsons,” he said.
Groening also designed the Simpson family to be immediately identifiable in silhouette - hence their distinctive hairstyles and head-shapes.
The likes of Lovejoy, Quimby, Flanders, Kearney, Terwilliger and Burnside are all real-life street names in Portland, Oregon.
There is a specific clause in the creators’ contract that the network can’t give notes, make cuts or exert creative control over episodes - meaning the producers have free rein to poke fun of FOX itself.
Hence the network HQ being a few well-dressed people in a trailer on a hill, Krusty saying, "You're Fox! »