Hi, I've been watching this show... a kid is playing pranks on the school staff... finally the headmaster asks him to follow him in the office... and he says "I'll grill your cheese yet!" Any help?
Guy, I'm completely clueless... by the way, awesome forum
I've never heard it before but I guess from the context it means that the headmaster is telling the boy that he will either:
Prove that the boy is the one who's playing pranks.
Or, if the headmaster knows that he's the one:
Punish the boy.
Edit: Oh, OK, if it's the boy who says it then ignore my post entirely. And either way, the expression is idiomatic, since idiomatic just means language use that is not taken literally. Unless one of the two is planning to literally grill some cheese belonging to the other, then it's idiomatic.