GG and Christian clarified that the Spanish duo is referred to as a 'tuna', a medieval Spanish fraternity of troubadours (usually students) who travel around singing for tips to pay for their tuition, traveling expenses, etc. The word is derived from "estudiante" or some variation of that word. These guys, Alejandro and Rafa, are traveling across the U.S. and then down the Pan American highway to the southernmost tip of Argentina, a trip that Christian has been dreaming of doing for as long as I have known him. They are, needless to say, inspiring and very sweet.
I videoed the song they played for us on the front lawn with the Flip. The lighting is terrible but the sound is good and I think you can appreciate how incredibly odd it all seemed...such a lovely, unexpected event.