make beer runs, a six-pack

[Humble]

Hi,
Could you please help me understand the highlighted pieces:

I only saw him on the weekends when he made beer runs for my high school buddies and me. We gave him a six-pack and ten minutes of our time for his trouble and then left him as we had found him, sitting at his kitchen table and […]and sipping a lukewarm beer…
BTW why a beer? I wouldn’t use the article.

Thanks.

[sandhya.sha]

Hi,
Could you please help me understand the highlighted pieces:

I only saw him on the weekends when he made beer runs for my high school buddies and me. We gave him a six-pack and ten minutes of our time for his trouble and then left him as we had found him, sitting at his kitchen table and […]and sipping a lukewarm beer…
BTW why a beer? I wouldn’t use the article.

Thanks.

Six Pack - six containers, usually bottles or cans of a particular type of beer or other drink that are sold together as one unit

a beer - a glass or container of beer

[Tdol]

A beer run- going to the shop to buy beer, usually a substantial supply.

[BobK]

And he took his brother because he and his friends were under-age (age restrictions are tight in the UK and very tight in the US). It had to be a substantial supply, as Tdol says, because his brother wouldn't want to take part in a risky expedition more regularly; also, because the friends pooled their resources, they could afford a lot.

He uses the article as it's an abbreviation for 'a drink quantity/glass/can of beer': 'I usually stop by at the pub for a beer on my way home.' [The bold marks my emphasis. The sentence stress is /fɘʀɘ'bi:ə/ .]

b

[Humble]

Aha, now I see what caused my misunderstanding – I couldn’t assume an adult being at schoolchildren’s service. (BTW I'm not sure assume is OK here).
Thank you all very much.

[BobK]

Aha, now I see what caused my misunderstanding – I couldn’t assume an adult being at schoolchildren’s service. (BTW I'm not sure assume is OK here).
Thank you all very much.

I think "imagine" would be better here - you couldn't imagine an adult....
(I don't know where I got the idea of an older brother from - maybe it was because I was reading about such a trip a few days ago.) Schoolchildren could get any compliant adult to shop for them - often a sibling, sometimes a friend, sometimes a random stranger.

b

[Humble]

That's exactly the word I had in my mind, but I was afraid it was a calque. I searched for sth similar and made a wrong choice.
Tnx, Bob.