Pterodactyl Greeting

A sound that emits from the mouth of one or more females when they run into one another after not seeing each other for no more than 2 hours. Even worse when the two females have not seen each other in months.

Observer #1: "WTF is that noise coming from those girls?"
Observer #2: "That my friend is the pterodactyl greeting for when two girls haven't seen each other since their first class of the day." (Observer #2 proceeds to flap their arms like a pterodactyl and mimic the screeching of the prehistoric beast.)