13TH BIRTHDAY HELP!!!!!!!!!!!!!!!!!!!1

Hey everybody! im havin my 13th birthday on sept 11...its co-ed and about 30-40 people
I have no idea what to do...my last co-ed party was great but some of the time we just sat around or were screaming at eachother trying to start a game or somthing...i dont know if i should have a theme or what...u could say we r pretty mature and dont like little kiddie games or themes anymore...please help...either here...or my e-mail is devorich132010@yahoo.com...and my screen name is devorich132010