Happiness is one of the four areas in Jim's brain in Earthworm Jim 3D. It has the entrance to the levels Lord of the Fries, Are you hungry tonite and the battle against Fatty Roswell.
Food is what makes Jim happy, that's why food is the theme of the levels. One level is at a volcano, which ground looks like cheese and lava is actually hot tomato sauce. The other level is in a building with a kitchen and a machine to make hamburguer.