I balanced this last week and it was still up today.
C. has a policy of not having symbols visible in his office. He does have one large and three small wooden ducks as part of the decoration. I found a matching small wooden duck, and added it to his collection. When he noticed it he put it away in a drawer. I said what harm is there in another duck, and he said he would think about it. Today he said that he had decided he couldn't have the duck I had given him out. Only he had gotten mixed up and he gave me back the wrong one. When I said I thought it was the wrong one he was quite convinced that he was right and I was wrong, until I pointed out the feature that proved which one I had given him. So I could have not only had my duck in his collection, but had one of his ducks in return. But it didn't feel right to trick him.