They steal bottles hidden by drinkers and sell them at a cut rate.
Fred Colvin bought the Gold Beach Confectionary during Prohibition in 1921, so he sold soft drinks and near-beer, but no alcohol. But according to his 8-year-old son at the time, Edsel Colvin, Prohibition didn’t stop anybody from buying moonshine.
Edsel and one of his friends noticed that some folks habitually bought pint bottles of whiskey from bootleggers, took a swig and then -- because nobody wanted to risk getting caught with a bottle on them -- stashed the bottles in a “hidey hole” before going into the confectionary to play poker and shoot the breeze.
Some of the men got so drunk they forgot where they had hidden their bottles, and perhaps didn’t remember having bought a bottle at all. Edsel and his buddy saw a golden opportunity. They simply collected the bottles from the hiding places, held on to them for a few days, and then sold them at a cut rate – sometimes even back to their original owners – at the back door of the pool hall.
It was an easy way for a kid to make a buck back then and more profitable than present-day lemonade stands.
Source: Colvin, Edsel. Got To Go Now: An Oregon GI Writes Home During World War II. Portland, Author House, 2013, pp. xv-xvi.