What I did for my party last year was I invited ALL of my friends (about 27). We all met at the house and hung out for about a half hour to 45 minutes. Then, once all the chaperones (parents of some friends) showed up, we were divided into groups.  We got in the car and our chaperones took us to the nearest Acme.  What we did is we had a list of about 80 clues for things to find in the store.  My mom had been earlier in the week making up the list. For example, one of the clues could be "Red vegetable 'M'm m'm good' soup".  You would then look in the soup isle for a soup's slogan that is 'M'm M'm good' (Cambells.  The red vegetable would be tomato. So the answer is Campbell's Tomato soup. We had about 45 minutes.  The losing team (the team that answered the least) had to sing the Barney song in front of the whole store! Believe me, you get some weird looks!  It's tons of fun. Remember to get permission from the manager or some other person of authority to do this.