El Gordo is the top prize in Spain's Lotería de Navidad, the Christmas Lottery draw held in Madrid each December, where pupils from the San Ildefonso school sing out the winning numbers. In the 2016 draw, number 66513 took the main prize, worth four million euros, and the sung announcement became a short clip shared by lottery fans and creators. It remains popular because the chant is instantly recognisable in Spain and works as shorthand for a sudden, enormous win.