I did not think of Harry Potter for that one. I thought of the ORIGINAL meaning of hogshead. It is a unit of usually liquid measure, most often referring to casks of alcoholic beverages like wine, ale, and cider. A hogshead is roughly equivalent to 2 barrels of liquid, or 63 US Gallons of wine, and 54 gallons of beer or ale. Note that the exact measurement does change depending on the year of “standardization” and what was stored in it. US Southern plantations in the 1800s also used the word hogshead as a unit of measure for sugar.

http://en.wikipedia.org/wiki/Hogshead

This meaning, large amounts of beer, ale, and wine, fits perfectly with a pub.