I was just watching a show about saloons on the History Channel. Apparently, the top hole in beer kegs, into which one pours the beer and into which the tap is later inserted, is called a bunghole. The device used to insert a plug or tap into the bunghole or drafthole (the hole on the side of the keg, used for ventilation to make pouring easier after the keg is tapped) is called the bunghammer.
So beer comes out of a bunghole after someone uses their bunghammer on it.
Just something to think about...
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"And Wirthling isn't worth the paper he isn't printed on."