I'm not getting a sense of who you are. You say not too girlie, but you're also talking about tiaras and dresses. You also mentioned you love parks and wouldn't mind a sort of hippie party. Depending on how many people you have coming (would this be friends, friends & family, or everyone you've ever met?) you could Go Green and have a recycling party or an Adopt a Highway event where you and your friends clean up litter from a mile of road.
Jai has created a Facebook community for this project and it's starting to pick up steam. But he still needs names---and if you want to honor someone anonymously, he can add ribbons for aliases or nicknames! We're trying to go global with this. Please help us make a statement and remember a person living with HIV/AIDS.
Serve "dirty" drinks like Dirty Martinis, Mudslides, and Sand in Your Shorts. Play Christina Aguilera's "Drrrty" cd. Paint tiny terra cotta pots with the theme and the date and fill them with potting soil. Give them out as party favors with packets of wildflower seeds.