Flute

n.

Heard in Galway, Tipperary, Mayo, Fermanagh, Sligo, Limerick, Longford, Cork and Dublin

A foolish, silly, or incompetent person whose common sense leaves much to be desired.

In use

Stop messin u flute before you break something valuable in the shop!

Posh English

Cease your foolish antics, you simpleton, before you shatter something of value in the establishment!

Same phrase, other counties