Botellón ("big bottle")
is a large group of people drinking together in a public square or park.
I've observed it only in Seville, but I believe it is a tradition in wider Spanish culture post-Franco no doubt; it doesn't seem like the kind of thing that would happen in a fascist dictatorship.
Indeed, the liberty allowed the Spanish to congregate in public and have a drink is astounding.
The first time I saw botellon was on a Thursday night, the beginning of a weekend, on Plaza San Salvador, a large ancient square in the center of town.
Hundreds of people gathered socializing, having a bit of drink or a smoke. Nobody was bothering anybody else, as far as I could see least of all the police, who were nowhere visible.
A large bottle of cerveza Cruzcampo, or a small plastic cup from one of the little pub-counters opposite the cathedral, or a glass of wine there might be a thousand individuals....
Afterward, early in the morning, city workers go around with sweeper machines and straw-twig brooms and clean up the broken glass and other debris.