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.
Sex-obsessed squeaker: Dude, she sounds hot! I would totally fuck her 100 times! Have you guys ever heard of Britney Spears? She's so hot, I would do her so hard. Did you just kill me? I'm totally going to fuck your girlfriend!
guy 1:"Shut up you squeaker."
(Mature Voice): Damn kid. Shut up and stop squeaking.
(High Pitched Squeaker Voice): SQUEAK SQUEAK SQUEAK