Who or what is a head the ball?

Travel Info
After a trip to Ireland i found a great book called "overheard in Dublin" it makes loads of references to a head the ball?? whats it all mean????

Travel Tips

Ha ha. I haven't heard that one in a while. It's used to describe someone who is mad or crazy. It's by no means scientifically accurate, but we all know someone of that description, right? It's just our way of describing such a person. Not entirely sure where it comes from though.
Others

In Scotland a heid the ba is a dafty :o)
pen bel, Welsh, ball head. nothing but air in it,
it generally means idiot!
Its a nutter
Someone who is stupid, crazy, daft.
lol after you've headed a football once to many times , it has an affect on your general intelligence and reasoning abilities , so "head the ball" is an statement on someones brain capacity lol in other words a numb-skull , numpty , nutcase etc etc , and is used in Scotland also.