My boyfriend needs to THICKEN HIS NECK for the ARMY?!
Question: how would he go about this>???
Answers: how would he go about this>???
The only thing I can think of that you are referring to is the body fat standard. Do they still use the waist measurement over neck measurement ratio to determine body fat percentage? If this is the case have him look into other methods of body fat measurement or make his waist smaller.
You do NOT need to have a neck of a certain thickness for the army. It may be helpful to be very strong in many ways, but a thick neck is not a specific requirement.
He should get advice like this from a certified personal trainer or authoritative literature on the subject because he could hurt himself badly otherwise.