What costume should i wear for a Halloween orchestra concert?

ok im 16 i play cello and our orchestra is doing a concert for holloween and letting us dress up i have two that i cant deside between http://www.costumes4less.com/Shrek---Gingerbread-Man-Adult-Costume_Z32088_Prod.aspx http://www.buystarwarscostumes.com/stormtrooper_costume_authentic.html but feel free to make any sugestions thanks!!!