What to wera to your friends sweet 16 when your only 14?

ok my fran is hvaing a party and i don't know antone that is going cause i'm the only person from the middle school who was invited and i don't know what to wear to a 16th b-day party it is going to be at the communtity lake house that her parents rented out but yeah it's not like wear a dress or summin fancy like that so what should i wear?