For free, costs nothing, bugger all, a freebie.

Very occasionally heard in public houses, when very nice landlords decide they are going to bequeath a punter with a free beer, either for a particular reason (birthday, engagement, blue moon tonight, hell freezing over) or just because the barkeep is feeling generous (equally rare).

Comes from a shorthand way of saying "The house is paying for this one"

Log in or register to write something here or to contact authors.