When your co-worker strips...

...it's probably because he is Japanese, and having to put up with a fairly remarkable government idea:

Takashi Kadokura used to strip down to his underwear when working late because of the heat.

"We couldn't concentrate on our work," said Kadokura, 37, then an economist for Dai-ichi Life Research Institute in Tokyo. "The air conditioning was set at 28 degrees and we weren't allowed to change it."

The experience led Kadokura to question the government's Cool Biz policy, which recommends companies set air conditioners at 28 degrees to reduce carbon dioxide emissions. Kadokura says sweaty offices lead to lower productivity, and estimates the policy reduced economic growth in 2008 by ¥653 billion, or 0.13 percent of the gross domestic product of ¥497.4 trillion

More details in the Japan Times: Cool Biz said to undermine productivity