Out like a light

phr.

Heard in Tipperary

To fall asleep very quickly.

In use

Was de youngfella ok for ya dad, ye warrent gone out de door, whin he was out like a light, an not a peek since.

Posh English

Was the young fellow satisfactory for you, Dad? You had scarcely gone out the door when he was fast asleep and not a peep since.