Lush

n.

Heard in Galway, Mayo, Longford and Sligo

To drink or imbibe in small quantities; especially, to take in with the lips in small quantities.

In use

Giz a lush of yer Bucky quick fast!

Posh English

Be a good sport and hand over a hearty sip of your alcoholic tonic with absolute alacrity!

Same phrase, other counties