I was really impressed to discover that someone else uses this excellent term. I use it as a 'mild' expletive when something happens that slightly annoys or frustrates me.
'You are joking, we haven't got another meeting tonight have we? What a cock-on-a-stick.'
'Cock-on-a-stick, where are my car keys?'
Derogatory slang to mean someone is an imbecile.
The word derived from my colleague sully when I was helping him move boxes and accidentally dropped a box on his foot.
Sully: "Chris you cock on a stick....you've just dropped that box on my foot"
Chris: "Your the cock on a stick for leaving your foot where the box would fall on it"