In a saucepan, combine sugar, water and corn syrup. Bring to a boil. When mixture begins to thread, turn stove to medium and add peanuts. Cook until peanuts looked parched (about 10 minutes). Remove from heat and add butter. Mix. Add baking soda and beat quickly and vigorously. Let rise to top of pan. Pour onto a buttered baking pan and let cool until hardened. Break apart and store in an airtight container.