Kix is a brand of cereal that is known for being kid-tested and mother-approved. This slogan implies that Kix cereal has been tried and approved by children, ensuring its taste and appeal to young consumers. Additionally, the approval of mothers suggests that Kix is a nutritious and wholesome choice for children. Overall, the slogan emphasizes the trustworthiness and quality of Kix cereal, making it a popular choice for families.