Lip syncing a song is a very easy idea that has been done to death on Youtube and sits a couple of notches lower than karaoke on the "talent needed" graph.
That us until it's done on a large scale with hundreds of high school students working together as a team to create something fun and inspiring:
This video obviously took a fair bit of planning, a steadicam and, as I said before, teamwork, but there's no reason why you can't do something similar at you school or workplace. Try showing this video to you boss/teacher/manager and pitching it as a Friday afternoon team building, moral boosting low cost, high reward activity.
Remember, projects like this should never be used as a reward for good behaviour or increased productivity but to encourage it.