[Lizard King]

Is there a correct way to do these without crushing your nuts? I haven't done them in a couple of years, been using dumbells and the shrug machine but am getting bored with both. Almost at the max dumbells and the shrug machine is a joke, I can do close to 700lbs on it. I decided to do barbell shrugs yesterday but I don't think I have a good form as I felt my back pulling and was playing hack i sack with the family jewels. I was able to get 4 sets in and 2 at 315, would have went heavier I think if I knew I wasn't going to hurt myself.
Thanks