squeakers
Preteen to midteen aged girls who flock together in malls and at social events.  

Term also applies to the noises these girls make, especially when they are startled or excited.

Such groups are called squaggles, as in a squaggle of squeaks.  Their male counterparts group in gaggles, as in a gaggle of geeks.
I like going to middle school basketball games just to watch all the cute little squeakers who get so exicted watching the game while simultaneously trying to remain cool.