I find that a soft little moan just as they approach the area does the trick.
This will not necessarily get you off scott free. I did the same exact thing and got a VERY invasive patdown which resulted in me almost decking the "agent" and filling a complaint. It does prove that the patdown procedure, much like the metal detector / body scan switcheroo, is completely random and prone to the whims of our TSA overlords.
The last time I flew, back in 2011, when asked that question I indicated that my groin was sensitive. The TSA agent paused for a second, said "Good one", and proceeded to violate my body by going places I only let girls go. That was it. I was done. (This was the third time in a row) I am not a criminal, I do not appreciate being treated as one, and frankly I am not going to pay to be treated like a criminal. I can get that for free.The way I get the TSA to not touch my junk is to not fly. I rather enjoy the road trips, and enjoy spending my travel dollars in the small towns and byways of this great and beautiful nation of ours.We live in a wonderful country; it's a pity what the government's doing to it.