Jaysus your as usefull as a ashtray on a honda 50

exp.

Heard in Wexford

You sir are unqualitified for the job and are useless.

In use

Jaysus get the fuck off that lad yur as usefull as a ashtray on a honda 50

Posh English

Good heavens, remove yourself from that fellow immediately, for you are quite as useless as an ashtray on a motorcycle.