Obelix says this to Asterix in the book "Asterix and the Laurel Wreath" by René Goscinny (stories) and Albert Uderzo (illustrations).
It is a louder and more forceful form of "exactly".
"We should get some wild boar."
"Nah... I'm too hungry."
more exactly than exactly , a confirmation or response.
"Now I know what you mean" ! (response )zigackly !