I was travelling in New Zealand recently. I went to a hot spring, and in the changing room there was a low-20s Chinese guy. While showering he left out his clothes, which had a pair of white briefs right on top.

After I finished showering I put on my tighty whities (Hanes) a couple lockers away from his. He came out and put on his briefs, which were just a plain white brief, like Jockey Elance.

He seemed very comfortable. Maybe this is common in China?

A bit later saw him leave with his wife. I saw several other guys with obvious brief lines on the trip, so I think they are a lot more common down under. Still mostly boxer briefs though.