The sound comes from the Spanish Christmas Lottery draw held on 22 December 2016, where the number 66513 won El Gordo, the first prize. Pupils from Madrid's San Ildefonso school traditionally sing out each number and prize amount, a style dating back more than a century. Clips of the four million euros call were shared widely in Spain as a shorthand for striking it rich, and the short chant has since circulated in chats and edits whenever someone talks about a windfall.