[slapfan]

I have a question for the Woman. Im noticing that before the fight starts alot of the woman nipples are hard. Why is that?

[DottiD]

Its from Adrenalin  rushing coupled with the emotional roller coaster we go through, confidence,fear,thrill, anger, jealousy so on.

[Cinnamon_Cougar]

They become engorged with blood is the correct clinical answer.  In layman's terms, we are turned on! 

[jessiefite]

I would go with, we are emotionally and physically excited, even if not "turned on."  Our endorphins are flowing, blood pressure is up, senses are intensified, fear, strength, vulnerability and anger are all mixed and bubbling to the surface.  We sense that conflict is coming and our bodies are physiologically preparing for combat.