He does the transaction with the teller, offer a polite bow accompanied by an ‘ah so’, and leaves.
He comes back in a week with another large amount of usd to exchange. This time he gets much less yen. He looks quizzically at the teller and she says to him, ‘fluctuations’!!
He angrily grabs the cash and storms out. As he’s leaving the branch he comes back in and yells at the top of his voice: ‘fluc you Americans too!!!’