Went trough there as well. It was to work the shots in so you wouldn't be sore from them.
Military shots...
At Parris Island when we went for shots they had a set of parallel bars with us lined up to go thru them. Two Corpsmen, one on each side, shot you in the butt at the same time with a needle. Then you stepped up one step and two more Corpsmen shot you with the hydraulic guns at the same time.
Well the guy in front of the guy in front of me flinched when they shot him with the hydraulic gun and it tore some meat out of his arm. He had some blood run down and drip off his elbow and the guy in front of me passed out. They just bent over and shot him lying on the deck and the rest of us step over him until he came too....
When we went for dental records and to get our teeth fixed I tried to tell them I didn't need any dental work done...
...they deadened half my mouth anyway. ...so dead my eyelid on that side was drooping... When the dentist got to me he said, "Get the hell outta my chair. You don't need anything." Went back the next week for the other side and came out with another drooping eyelid....
....the military has their own way of doing things.