Dry arse

n.

Heard in Cavan

A dull, dreary, or uncharismatic person who drains the merriment from any gathering.

In use

Yawn lads, yer man is a proper dry arse so he is, just sittin' dere like a spare wheel.

Posh English

Good gracious chaps, that fellow is a remarkably tedious bore, merely sitting there in absolute silence.