1. The biggest dickhead you know is likely to be a Class A DICKHEAD as they top the list of biggest dickheads of all time. Everyone thinks they are a dickhead.
2. Term used to describe people who are addicted to Class A illicit drugs such as Heroin or Crack.
3. A politician who talks bullshit (possibly all politicians)
A Chav who steals your bike is likely to be a Class A Dickhead.
A meth addict could be described as a Class A dickhead