Not the pretty ones…the bad ones.
I get this question alot when I am talking to students and we get to the part where I speak of small talk and starting conversations. Butterflies in the stomach is the bodies flight or fight response. Basically during your bodies fight or flight response, blood is drawn away from the stomach or vital organs and sent to the major muscle groups. In addition to this, adrenaline shoots through the system ready for the impending flee or ass-kicking you are about to render.
Butterflies are often experienced prior to public speaking, important meetings and other occasions your body (and mind) sees as dangerous.
The cure? Relax, breathe, maybe eat a few crackers to settle the stomach.