It was an odd sight - a half-dressed man scurrying round a corner carrying a clear polythene bag of amber liquid. Maybe it was someone on the run from the local hospital, catheter in hand.

If so, the hospital had a mass breakout on its hands, because there was another one further along the street. Then another, this time a woman, all in a hurry and all clutching bags of what?

I was traveling through Qingdao, having just arrived for the opening of the city's two-week international beer festival. I hadn't touched a drop yet, and my finely honed investigative journalistic talents pointed to the guess that this had more to do with beer and the sweltering heat rather than, say, billing problems at the local clinic.

Perhaps they were giving away free beer to commemorate the occasion, the 23th such festival, the biggest, best, most beery etc. Or it could have been overstock or beer siphoned from barrels that had fallen off the back of a lorry enroute to the festival (wink, wink, say no more).

Indeed it was beer. (I asked someone.) Qingdao's finest in fact, Tsingtao. So good they named the city after it - or something like that. I'd had a beer or two myself by this time.

Now, there's a great new concept I thought - Beer in a Bag. In fact, the good burghers of Qingdao have been doing these beer takeaways, or slosh-aways, for nigh on 40 years. All the little local shops sell it chilled direct from the keg for around 30 cents a liter. It's particularly popular in the long hot summers. That's why they were running - to get home and drink it before it got warm.

The custom started in the 1970s when those who fancied a quick brew collected it in open bowls. Then in the '80s, probably after realizing they were losing half of it in transit, they changed to glass canisters, the kind used to drink tea.

That still limited most to half a liter, so the next decade in came the polythene bags, knotted at the top, which have proved enduringly popular to this day.

I know all this because after watching the mayor of Qingdao officially open the beer festival (with a ceremonial wooden hammer and giant barrel, no bags involved) and then, having quaffed a stein or two just to be sociable, I hopped over to visit the original brewery at the other end of town, which now incorporates a museum and where unavoidably, I imbibed some more of the local, world-renowned laughing juice.

You only get two noggins as part of the admission price, one of the raw, unfiltered stuff, one freshly brewed, but I got more because people were being extra hospitable.

As well as ghostly apparitions of ancient braumeisters, I saw the oldest Siemens motor in China, used in the brewery after it was built by the Germans in 1903, helped by some British businessmen (not many people know that). Eleven years later the brewery was taken over by the Japanese, who, as it happened, made the beer better (not many people know that either). And that, of course, eventually Tsingtao became a Chinese export success story, after silk, tea, porcelain, fireworks everybody knows that!

But beer in a bag, who would have thought of it! I'm off for another beer in a tent.

Contact the writer at sundayed@chinadaily.com.cn.