Spare tool

n.

Heard in Waterford

Someone who is surplus to requirements, a gooseberry, a person who feels uncomfortable in the company of an amorous couple. Also: Someone who is useless.can also be shortened to just spare.

In use

Christ boy I felt like some spare tool with them pair" "Your man is some spare tool!

Posh English

Good Lord, boy, I felt like a superfluous gooseberry in the company of that amorous pair.