Get him something that he always says he wanted but hasn't got it yet.
Party ideas = Backyard Music and Dance Party
One teen wanted a "party in the backyard with music and dancing." Theme suggestions: Tiki party, BBQ party, or any outdoors theme, or no theme at all. Invites say, "Hey - Come Hang Out in My Backyard and Dance!" Provide great music.
Have a karaoke or bowling competition.
As a joke, do each others makeup and hair.
Maybe invite the guests and on the day of the birthday. Ask the birthday girl what she wants to do and do that.
I am assuming the birthday person is a girl because I know you kevin..haha