Shepard was screaming at you, he was all in your face. You only said 'AYE SIR'. he lost his cool after you just kept saying it, He expected you to break and stop, he wanted a reason to actually yell at you, for breaking protocol. But you kept your head straight and you stood at ease. You looked more annoyed than scared.

Shepard: "I SEE TEARS? PRIVATE DO I SEE TEARS?"

Ghost, price, gaz, Alejandro, roach, soap, keegan, and Logan stared at you in disbelief. You were all 18 year old privates and you looked like you had 40 years experience.

Sheppard stormed off to go harass a different rookie as you say back down on the grass, the whole stream of guys next to you just gawked, grinned, or hyped you up quietly.