Preteen girls squeal and scream as a group – a powerful bonding experience. They can get emotionally overwrought and faint from the excitement.
Male audiences are more likely to get the group experience by pumping their fists in the air – in unison.
In both cases these behaviors reinforce their connection to one another – a moment of transcendence (albeit the teen version). Anyone who stands in their midst and does not participate – may be seen as judging. This won’t endear them to the group.