I guess that if you fly the JR under a national flag, it is seen as ornament. If it is on its own, then the issue is not so much that you are flying it, but that you are not under any national flag, which I believe is a serious matter. So what marks you as trouble is not that you have the skull and crossbones but that you are not identified properly.
I’m thinking of putting one on my kayak, if I ever actually go get it. Maybe waylay some boy scouts in their canoes and steal their candy (and patches).
Yarrr!
What if you simultaneously infringe on copyright by downloading music through a satellite connection? 
In the 80s a bunch of us rented a barge for 7 days and sailed up and down the Thames. We flew the Jolly Roger because…well we were young and stupid.
Nobody batted an eyelid.
Nobody threw balls accross your stem, huh?
(Or is that “bow”?)
Not much on TV so I was watching San Francisco vs Oakland (my home-town team) and realized what their emblem is. 
pretty close.
You can tell how much of a fan I am.
The Pittsburgh Pirates are a little more direct. The old logo: http://sonsofsamhorn.net/wiki/index.php/Image:Pitt_Logo.gif, and the new: http://www.sportslogos.net/images/logos/54/71/full/1275.gif
