Ideas for an 18th birthday?

I am stumpted on what to do. Everywhere i look people are going clubbing, parties, road trips, limo/hummer rides, shopping sprees etc but i want something different and unique and i cant think of anything. Its not for a few months btw but id like to start planning now. Also my best friend and i were thinking of joining our birthdays 18ths together except hers is in January and mine is in May. I dont know what to do?