Hmmm..sometimes I think researchers have too much time on their hands. Perhaps "Tom" the scientist gets a better reaction from colleague "Jenny" (or "John") during a coffee break than during after-work drinks. Perhaps it may be more to do with quantity consumed than the temperature of the drinks but it also depends on whos buying!

http://www.smh.com.au/news/lifeandstyle/relationships/are-drinks-a-sign-of-character/2008/10/24/1224351504812.html

Judgment of character can be influenced by something as simple as the temperature of a drink held in our hands, according to a US study published today.

Researchers from Yale University conducted experiments that showed that people perceive others as more generous and more attentive if they have just been holding a hot cup of coffee, and that the inverse is true for cold drinks.

A second study found that people are more likely to give something to others if they held something warm, and more likely take something for themselves if they held something cold.