The Happy Tail Movement is a grassroots organization that works to promote the adoption of shelter animals. The term 'Happy Tail' refers to the wagging of a dog's tail when they are happy and excited. The organization works to raise awareness about the importance of adopting animals from shelters, as well as providing resources to help people find their perfect pet. The acronym WAG stands for 'We Are Grateful, ' which is the motto of the Happy Tail Movement.