Mayday for Mutts is celebrated on the first Sunday of May to promote love and acceptance for mixed-breed dogs in the United States. The holiday encourages adoption from animal shelters, aiming to provide homes for these lovable animals. The term "mutt" originally referred to half-breed dogs, but has evolved to describe mixed-breed dogs without specific lineage. The celebration highlights the importance of mixed-breed dogs, which have gained recognition through events and organizations like the Mixed Breed Dog Clubs of America and the American Mixed Breed Obedience Registry. Typical customs associated with this day include raising awareness about the benefits of adopting mixed-breed dogs and supporting local shelters.