To be honest, neither side can control the erection of your penis, it has its own consciousness.
Frankly speaking, I don't believe that you can stiffen it in front a dinosaur-kinda-girl unless either of you force it.
On the other hand, your penis may launch itself without your consent in the early hours of the morning, well, if and only if you are a healthy normal male.
Those are basic science facts, and so are the pulse of monetary market. A government has only limited control over its exchange rate in modern world economy. Not matter it is Chinese government or the ever-powerful government of the united states of America.