What is "puzzle jug"

A puzzle jug is a puzzle in the form of a jug, popular in the 18th and 19th centuries. Puzzle jugs of varying quality were popular in homes and taverns. An inscription typically challenges the drinker to consume the contents without spilling them, which, because the neck of the jug is perforated, is impossible to do conventionally.

The solution to the puzzle is that the jug has a hidden tube, one end of which is the spout. The tube usually runs around the rim and then down the handle, with its other opening inside the jug and near the bottom. To solve the puzzle, the drinker must suck from the spout end of the tube. To make the puzzle more interesting, it was common to provide a number of additional holes along the tube, which must be closed off before the contents could be sucked. Some jugs even have a hidden hole to make the challenge still more confounding.