This is a physical warm-up and ice breaker. One person in front, with two people behind her and three behind them, forming a pyramid.
This is best done with music, but you can improvise around that. The first person starts to move or dance. The two immediately behind her mimic the movements. Each row follows the row ahead. It is fun to watch the movements decay as the line gets further back. The leader alternates as the music changes, or as others come forward from the back ranks.
The lead person turns around so the flock must turn around, but can no longer see what is happening. Doing the splits ends it quite effectively as well.