A corner shop with an off licence, that specialises in serving cheap, poor quality alcohol. These people seem to have a licence allowing them to sell beer to anyone over 12 years old.
A Beeroff, Beer-off or Beer off is a colloquialism for an "OFF-LICENCE", commonly shortened to "Offy", a shop or other commercial outlet which is allowed to sell beer, wines and spirits to be consumed OFF the premises, unlike pubs, bars and similar places which are LICENCED to sell alcoholic beverages to be consumed ON the premises.
Initially a competition where people passive aggressively proved their superiority to others by drinking more than them, even when it was not clear to everyone in attendance that a competition was taking place, the term has grown to mean any gathering where beer is aggressively consumed.
"Hey, are you going to the beer off tonight? The one on the shore?"
"Before I answer that, let me grab my second beer."