Well, i think that because youve seen characters like Yuna n Paine, she seems like she's acting childish, but a matter of fact is, i no quite a few 17 yr olds that act like that (not nessaraly the language but, her speach IS a bit childish) as for in 10, shes 15, all my friends r 15, and we all act pritty much just like that! I dunno how all u guys act, but being childish is fun on a bun
I use the word "poo" alot, and like to see how many crackers i can fit in my mouth, i just think shes more fun loving and cheery than every1 esle, by ALOT so it looks like shes acting alot more childish than she really is.