A snug in Ireland is a small partitioned-off section of a bar with a window into the bar, where men can go to have a private drink and conversation; it was also often the place where women went for a drink together.

Pails of porter: it was the norm for someone (often a child) to be sent to fetch a pail - a billy-can containing a pint or a couple of pints - of porter (kind of like Guinness but a little weaker) for the women of the house in working-class city households.

A jar, as various people have said, is a drink. When people are in a phase of being enslaved to drink they're said to be 'on the jar'.