Preheat the oven to 375 degrees F (190 degrees C).
In a large bowl, stir together the peanut butter, water and eggs until smooth and well blended. Stir in the cake mix. Use your hands if necessary to blend thoroughly. Roll into walnut sized balls or drop by spoonfuls 3 inches apart onto ungreased cookie sheets. Press each cookie down using a floured fork.
Bake for 8 to 20 minutes in the preheated oven, until golden brown. Remove from baking sheets to cool on wire racks.