Clatter

n.

Heard in Waterford, Kilkenny, Westmeath, Dublin, Tipperary, Cork and Galway

A slap or blow, often to the head or face.

In use

If you don't leave me alone I'll clatter the face off ya!

Posh English

If you do not desist at once I shall deliver a resounding slap across your countenance!

Same phrase, other counties