Knock ‘Em Dead, Kid was track number nine on Motley Crue’s 1983 album Shout at the Devil. According to the Crue’s Wikipedia page, the song was inspired by a violent encounter between Sixx and a group of Hells Angels. Sixx somehow or another wound up in a fight with a group of bikers, even hitting one member in the face with a chain he had been wearing as a belt.
The Hells Angels turned out to be undercover cops, and the bassist was subsequently badly beaten and jailed, resulting in a black eye and broken cheekbone. After being released from jail, he was inspired to write a song about the ordeal.