(n.) referring to that of younger girls, usually teenage, that are superficial in nature, and they are very 'sqeaky'. They're fake, and they usually possess identity issues. They don't know who they are, so they copy off of a popular icon and think they own the world. Also, they don't have a clue - about anything really.
Michelle: Wow, look at that cute guy over there working at Dairy Queen. He shouldn't be working there, he should be a model.
Heather: Yeah, but he's a player. Look at him flirting with those yippees!
an exclamation similar in meaning to yahoo
Yippee! I won the lottery!