Sentence:  A <WSD>pony keg</WSD> (a few survive to this day) is a drive-through structure with cases of beer stacked on skids — golden liquid mountains, lining the walls of elongated garages or steel Quonset huts, looming above the consumer ... Our <WSD>pony keg</WSD> of choice was on Montgomery Road, on the Norwood-Pleasant Ridge border, a small affair next to a hairdresser's, neatly tucked behind the drugstore at the corner of Quatman and Montgomery. 
Meaning of the word marked with <WSD> tags:  A drive-through liquor store; "by extension", any convenience store.