Bom dia @rmach

The 'porró' is a nice catalan traditional way of drinking wine. The most common wine to drink with it is red wine, and usually not a "bottled" wine but a wine from wine boots. It uses to be what in catalan we say "un vi que li fot" or in spanish they say "peleón" (a "fighting" wine, a hard tasting wine with high alcoholic grade).
As you say, you need some technique to do it. When I was young my parents show me how to do it, but didn't put some wine on it, it was still water!! Nowadays its use has decrease a lot, but in little towns and mostly in the Pyrenees towns is still very common.