there appears to be a part of the brain responsible for puns.

When the surgeon began to manipulate the tumor, affecting those sensitive structures, the (conscious) patient burst into a manic flight of puns. He exhibited typical sound associations, and with every word of the operator broke into a flight of ideas. The sound of one word swiftly echoed in the sound of the next, and all of the words had something to do with knives and butchery.