Slang for Herpes. This is used when a friend that never had chicken pox thinks he's finally caught them. He is wrong. CHICKEN Pox are everywhere. Cock Pox, well...
'Yeah, Sean, I have chicken pox, I'm Home and very itchy!"
"But Rob, your Twenty?! Oh... You've got Cock Pox haven't you?"
"Good show, mate, Good Show indeed."