The core temperature for the human body is 98.6 degrees Fahrenheit but the skin temperature varies depending on our emotional state. People who are described as 'cold' are usually also physically cooler people because their blood is drawn into the leg and arm muscles for the 'fight or flight' response created by tension. So when you call someone a 'cold fish' you are correct on both the emotional and physical levels. Conversely, when one person is attracted to another, their blood rises to the surface of the skin, making them warmer.

This is why lovers who are in the 'heat of passion', give a 'warm embrace', have 'steamy encounters' and can be 'hot stuff'. In many women, this increase in body temperature can be seen as their chests will become flushed or covered in red blotches and their cheeks also flush.