A friend and I started calling each other 'Chod-Head' in 1985. It is a derogatory term in general and not too specific (like many minor profanities).We thought we had made it up but many people in our place of work (about 8000 at the time) started using it.
'He's a complete chod-head' meaning dick head or stupid git.
'He's a total chodder' meaning that he can't do anything right.
'You're a raging chod'
However they came later CHOD HEAD was the original statement and came in total exasperation of anything else to say about the man we were describing.