Of all the problems with this study. . . of all the guys that will worry about their fertility and still have millions of "just fine" sperm. . . of the population argument and the billions of people on earth. . .
All I can think about is that this study started with some guy rubbing one out in the name of science.
I'm not exactly sure which country you are from, but here in the U.S. a billboard is never a "sign. . . [that] doesn't do anything."
There are billboards that recognize your car and greet you personally:
http://www.nytimes.com/2007/01/29/business/media/29cooper.html
There are billboards that aggregate the fm radio stations being listen to in passing cars the show the advert most likely to target the largest percentage of passing drivers:
http://www.nytimes.com/2002/12/27/business/media-business-advertising-new-billboards-sample-radios-cars-go-then-adjust.html
Interactive advertising inundates our modern lives. You're individual concerns aren't worth as much as the advertising dollars spent on you. No one cares that you feel like your privacy is being trampled, you're a target demographic and consumer. That makes your interests important only if your spending money. Opting out only makes advertisers not care what your opinion is because you are a "fringe demographic".
On a personal note, I still hate interactive movie posters. Ever since I walked past a poster for Step-Brothers and Will Ferrel scarred the piss outta me by suddenly coming to life and badgering me to come see the movie.
IF I HAD A MINE SHAFT, I don't think I would just abandon it. There's got to be a better way. -- Jack Handley, The New Mexican, 1988.