Lyric discussion by twiztidfreek 

Cover art for Rooster lyrics by Alice in Chains

It was written by guitarist Jerry Cantrell for his father, who served in the Vietnam War. His nickname was "Rooster."[2] The nickname most likely originated from men who used machine guns (see the second verse, first line) as when it would strafe an area the tracers would make a pattern that looked like a rooster's tail, but there is speculation that it may have been in relation to the 101st Airborne Division, in which Cantrell's father served. The 101st Airborne wore patches on their arms featuring a bald eagle. There are no bald eagles in Vietnam, so the closest thing to which the Vietnamese could reference them was the chicken. They referred to them as "chicken men".[3]

In the liner notes of 1999's Music Bank box set collection, Jerry Cantrell said of the song:

It was the start of the healing process between my Dad and I from all that damage that Vietnam caused. This was all my perception of his experiences out there. The first time I ever heard him talk about it was when we made the video and he did a 45 minute interview with Mark Pellington and I was amazed he did it. He was totally cool, totally calm, accepted it all and had a good time doing it. It even brought him to the point of tears. It was beautiful. He said it was a weird experience, a sad experience and he hoped that nobody else had to go through it.[1]

Source: Wikipedia