Written by Flaco's father, who was also nicknamed 'El Flaco' when he was young and slender. Learned to play accordion from his father, who learned it from his. Flaco's son Santiago (sic) continues this family tradition. See also: Ay Te Dejo En San Antonio.
Song about Mexican laborers, lacking a green card (licensia), swimming across the Rio Grande river to enter the US, hence 'wetbacks'.