My son had this party when he turned 11 and he and his friend thought it was hilarious. The friends still ask to do it again.  Come up with some dares around town (nothing disrespectful) and have all of your props ready if necessary and then make the kids draw out of a hat for their dare. This is how we started...we drove to a local park and made everyone jump out of the vehicle and run around a statue 3x and the last one back drew out of the hat first. We had dares like they had to run into a local store wearing a mask and cape and ask for a floodlight for the batsignal, go into a local grocery store with a colandar on their head and alien accessories and buy drinks for everyone and say it was fuel for their spaceship, walk around a public place with toilet paper hanging out of the back of their pants, things like that. You can come up with your own dares but be sure to take pictures!!