Spacer

n.

Heard in Limerick and Cork

An eccentric, foolish, or unreliable person who is slightly unhinged.

In use

Go way ouvit u spacer, ye haven't a clue what you're on about!

Posh English

Take your preposterous behaviour elsewhere, you absolute simpleton, for you possess not the faintest idea what you are discussing!

Same phrase, other counties