Sham

n.

Heard in Cork, Waterford, Clare, Sligo, Donegal, Limerick, Mayo and Galway

A tough fellow, street fighter, or general hard man.

In use

Looka the sham over there flexin' like he owns the town la!

Posh English

Observe that formidable fellow over there posturing as though he owns the parish!

Same phrase, other counties