One definition- a lug is a container for fruit, etc., about 17 inches long, 13 wide, and 7-8 deep.
But I remember the much smaller container, oblong basket-shaped conainer with a handle, in which we used to buy grapes. It was about 15 inches long by 7 wide and 5 deep (narrowing toward the base). I still have a couple. We incorrectly called these lugs. They were used sometimes as a lunch box.
More likely, however, the scout leader censored jug and made the boys substitute lug.