Mix the peanut butter, eggs, milk, and half of the cake mix in a large mixing bowl, using a wooden spoon until well blended. Mix in remaining cake mix with a spoon until blended and all dry ingredients are moistened.
Place sugar in shallow dish. Drop dough by tablespoons onto prepared cookie sheets. Or roll the dough into balls and roll them in sugar before putting them on the pan. Then take a fork, dipped into the sugar and make criss-cross patterns on each cookie. Bake for 10-12 minutes or until set at edges and just barely set in the middle when lightly touched.
Cool on the baking pan 3-4 minutes before putting them on a wire cooling rack.