What to get a girl for her fifteenth birthday?

I have absolutely no clue what to get her. I was invited to her 14th birthday but i decided not to go and she was pissed. So im going this year for her 15th birthday on the 20th. But i have no clue what to get a 15 yr old girl, since im a guy. My mom sugggested bubble bath or something from bath and body works but idk. So just some suggestions would help... and no, im not gunna get her a vibrator (even though it would be hilarious) thanks, best answer 10 points!