The last time I read about a roadside sign being "hacked" all the person did was walk up to it, put in the factory default password (the one they tell you to change) and they made it say "zombies ahead." Prior to the change it simply said traffic ahead. So people should quit flipping out and should look at the bigger picture. If caught should the person be punished? Yes, but the punishment should fit the crime and if no one was hurt, it wasn't a vital sign, and it wasn't properly secured then it shouldn't be a huge deal (id be more concerned with the sign not properly secured because that means other signs are likely not properly secured and terrorists could potentially use that to change vital signs and sow fear and terror).