From the word copper-scalp, refering to somone who is both stupid and a wanker. However, it is most commenly used for somone who, due to their own stupidity, makes thw wrong decistions and ends up being a heavy-set nobody.
" U-Turn only you piss-faced scalp!" -My dad
"Jeez, you can be a real scalp sometimes"-Me to my friend after he parked his car halfway up a hillock and forget to put the handbrake on. It knocked his dads fence over.