Hunt the Leader

This was one of my favorites.  We would take the youth group to a large shopping mall or main street (depending if it's day or night) and all the youth leaders would dress up or disguise themselves somehow.  We'd have a homeless looking man, a guy with a mustache, a girl with a pillow up her top to make her look pregnant.  Some costumes were a bit ridiculous and the leader would stand out, others were really subtle yet effective.  Also have a combination of youth leaders sitting in the one spot (like a cafe) and others wandering around (like a cleaner with a broom). 

The basic idea is to split the youth into groups and their job is to 'hunt' down the leaders to get their signatures (or stamp) on a piece of paper.  The winning group is the one that first finds all the leaders. 

A note of caution - ensure the young people are adequately supervised.  Depending on the age of your group, you may need to ensure there is a leader (not in disguise) with each group for their safety. Also ensure the group is aware of the 'boundaries', and have an agreed time to meet back.