What to wear at Christmas Concert?

I'm a 13 year old boy and I have a christmas show coming up, and I'm performing with my friend singing All I want For Christmas Is You. I'm not into fashion at all and I barley give 2... about clothes. I have, like, 1 christmas top... I have no "Cool Clothes" whatsoever. I just want it to be a great show!!! This is like my favorite christmas song and I want to get it right for me and her singing it! Also my parents may refuse to buy me more clothes because I hardly wear the stuff I have! I have one hoodie thats about a year old (I'm not poor, I just never dress up...) Bottom half is sorted.. I just need either a cool top or a cool hoodie... What should I do?