I've never heard of "chickenhead" being used as a slang term. I have heard of "chickenshit" though. In fact, I've known several people who deserved that title.
The name I see being used for what is basically a bean bag toss contest is a good example of why people should be careful before they start using slang terms. They call it a "Cornhole contest".
Now, when I was young, we used that term all the time but it wasn't complimentary and it didn't have a thing to do with throwing a bag of something thru a hole in a board.
No. Where I come from cornhole was another term for anal sex.