Stop the lights

exp.

Heard in Cork, Dublin, Sligo and Kerry

An exclamation of utter disbelief, astonishment, or shock.

In use

Ah stop the lights girl, you never told me she eloped with the butcher!

Posh English

Good gracious, young lady, you omitted to mention that she absconded with the purveyor of meats!

Same phrase, other counties