The U.S. Dollar is probably the worlds most used currency for drugs, sex trafficking, and other illegal behaviors.  Yes, those bills in your wallet have probably been in the hands of people behaving in illegal and immoral activities.  I do mean, take a $1, $5, or $20 out of your wallet and I am talking about that particular bill.

So, if you are worried about BTC being used for those purposes, what do you suggest be done about that currency in your hand?