I came across the Tuna de Medicina do Porto on myself way through town this morning. At first I thought they must be Jewish or Romanian or something but they are actually Portuguese. Wikipedia says "A tuna is a group of university students in traditional university dress who play traditional instruments and sing serenades. The tradition originated in Spain and Portugal in the 13th century as a means of students to earn money or food. Nowadays students don't belong to a "tuna" for money nor food, but seeking to keep a tradition alive, for fun, to travel a lot and to meet new people from other universities."
It's impressive that these students were studying medicine but still had time to play musical instruments and learn to sing in harmony to a professional level. I guess if they ever give up the day job, they will be set!
I was impressed by the fact that they just arrived from Australia, were probably jetlagged but seemed to be singing and playing music just for the fun of it rather than hawking tourists. Even though they could've made a killing with their talent! I wish them well on their journey and next performance wherever it may be.