buy you a drink?

(Can I) buy you a drink?

1. Would you like me to purchase you an alcoholic beverage? When used literally in this way, this offer is usually extended (at an establishment that serves alcohol) to a friend or someone with whom one is pursuing a relationship of some kind, often a romantic one. Hi, I couldn't help but noticing you from across the room. Can I buy you a drink? Hey, pal, I'd love to catch up. Buy you a drink?
2. Can I make you a drink? In this usage, the phrase is used humorously, since the setting is not a place where alcohol is for sale. A: "Buy you a drink?" B: "Ah, I'll just have whatever kind of beer you've got in your fridge."
See also: buy

(Could I) buy you a drink?

 
1. Lit. Could I purchase a drink for you? (An offer by one person—usually in a bar—to buy a drink for another. Then the two will drink together. Also used with can or may in place of could.) When Sally and Mary met at the agreed time in the hotel bar, Sally said to Mary, "Could I buy you a drink?"
2. Fig. Could I make you a drink? (A slightly humorous way of offering to prepare and serve someone a drink, as in one's home. Also used with can or may in place of could.) Bill: Come in, Fred. Can I buy you a drink? I've got wine and beer. Fred: Great. A beer would be fine, thanks.
See also: buy