Ideas for my thirteenth birthday?

My birthday is on June the second and I'll be turning thirteen. In previous years I've chosen one friend and gone to a movie then gone out to eat afterwards, but I'd like to do something more interesting this year. I can't throw a party and we're pretty tight on money. I'm planning to hang out with my two best friends - a guy and a girl - either together or separately. I also don't really want to do something that is birthday-specific because I don't like making it totally obvious that it's my birthday. Sorry if I'm not being very clear. :\