Answer:
Locked and cocked is a term usually associated with a firearm, although it is usually said "Cocked and Locked". This refers to arming the firearm, that is the gun has a bullet chambered and the hammer is cocked and the gun will fire if the trigger is pulled. Locked means the safety is engaged. Cocked, locked and ready to rock is a longer version of the phrase. It just means you are ready. You are fully prepared to do what needs to be done.