This is a night-out word, mostly British, Australian, and New Zealand. It means drinking alcohol at home, or at a friend’s place, before you go to a bar, club, concert, or party. People do it because drinks outside cost a lot, so they get a bit drunk first, cheaply. It is informal. Young people say it; a teacher or a news reader would probably say “drinking before going out” instead. Americans usually call the same habit pregaming — same idea, different word. Though actually, people sometimes stretch it a little: not only beer and shots, but “getting in the mood” before an event. The same spelling is also a computer word (loading data early so a page or game is ready), but this entry is the party meaning.

預喝酒、出門前先喝