There is a colloquial connotation to the word "flake" in ireland. To flake something typically means to hit it (e.g. he gave him a flake in the forehead, or the teacher used to flake us when we got something wrong).

This word is still used in colloquial and idiomatic speech in Ireland today. In the context of music (fiddle or otherwise) to flake out a tune would mean to play with gusto and power.