I can't believe I forgot to write this game down, and I now can't remember when we played it, but it was good.
Players line up facing each other (it's good if it's not 100% clear who your "partner" will be).
Start at either end of the two lines. The two "end" people each choose a walk, and walk towards each other. When their paths cross, each person takes the other person's walk, and finishes walking to the other line doing their walk. Go down the lines until everyone has changed places.