What are some good icebreaker games?

I am doing a pre-selection presentation for a Toronto Parks, recreation and forestry Camp Leader position. We have to present a song, a game, and a strength. I have the song and the game but i can't think of any strength presentations. I do not want to bring any instruments in( otherwise i'd be fine) and I don't want to do a craft. There will be 20-40 people that have to be involved and it can't be too long. I think all in all i have 6 minutes for my entire presentation. If you can think of any ice breaker games or anything else that i can do, i would be very appreciative. Thx