The L.A. Times does some trendspotting in China:
"From the countryside to sophisticated urban centers such as Beijing, men of all ages, social standing and stomach sizes resort to a public display of skin, a hot-weather fashion faux pas that's the Chinese equivalent of knee-high black socks with shorts. They're known as bang ye, or 'exposing grandfathers'(despite their age range). In the hottest weather, bang ye seem to be everywhere, striding among the tall buildings in Beijing's business district, playing chess in parks, holding children's hands at the zoo and negotiating crowded alleyways. There are precious few washboard abs among the lot. Still, many fail to notice that they're drawing smirks from fashion-conscious passersby. Most just don't care."