UDEF stands for Unidad de Delincuencia Económica y Fiscal, the Spanish National Police unit that investigates economic and fiscal crime, fraud and money laundering. The phrase De quién De la UDEF circulates online as a short Spanish audio meme detached from any single broadcast, shared in political threads and messaging chats. Its appeal comes from that real institutional name, which instantly suggests an official investigation, so users drop the clip whenever a conversation turns to unexplained wealth, raids or public money in Spain.