Sometimes after a big football game fans will riot, getting into fights and destroying property. people in such a crowd will often do things that they would never do on their own. this effect is due primarily to a process of:

adrenaline and peer pressure in tandem can cause a person to do things that they would never do on their own. A social construct is created for example, in the presence of others destroying property or getting into fights, or even better when societal standards allow the environment actions to take place, through past conditioning, so a person's action can be altered, without anyone currently their to pressure them or cause adrenaline.