The #WearYellowForSeth campaign began in March 2015 as a heartwarming social media movement to support Seth Lane, a young British boy born with Severe Combined Immunodeficiency (SCID). His parents posted a video asking the world to wear Seth's favorite color, yellow, on March 27 to cheer him up before his second bone marrow transplant. The request went viral, with millions of people, including celebrities and organizations, posting photos of themselves in yellow garments. Today, the meme serves as a powerful symbol of solidarity, courage, and global awareness for children battling rare immune disorders, turning a personal struggle into a worldwide message of hope.