Call de coastguard!

exp.

Heard in Cavan

Said if your opponent in a game of pool is kickin your arse I.e. he's a pool shark.

In use

Jaysis! wud someone call de coastguard! dersh a shark on the loose hee-er

Posh English

Good heavens, would someone summon the authorities, there is a most proficient billiard expert abroad in this establishment!