Botellón is a custom that takes place mainly in the Spanish nightlife, which involves the gathering of a large number of young people mostly between the ages of 16 and 24 outdoors to drink beverages previously acquired in shops (usually supermarkets), to listen to music and talk. This is often done because of the high prices in bars and being underage for bars and clubs.
The word botellón is an augmentative of botella (bottle) so the literal translation would be "big bottle".
Botellón is also used to refer to a drinking pack consisting of an alcoholic drink bottle, soft drink and ice. It is also known as botelleo, botellona, or botelloneo.