This isn't an urban legend?
Sounds like the middle paragraph here:
http://www.worldwidewords.org/qa/qa-tap1.htm
"Similar ghoulish tales have been told in many circumstances, including one of a couple who bought a house that had once been an inn and who were delighted to find that one of the old casks in the cellar still held rum. Only after they had emptied it and cut the cask in two to make plant containers for the garden did they find the well-preserved remains of a man inside. Jan Harald Brunvand, the American academic who has made a lifelong study of such legends, has told versions in one of his books, including a related one dating back six hundred years about some tomb robbers in Egypt. Other tales tell of containers holding similarly preserved bodies of monkeys or apes that spring a leak on their way from Africa to museums; the leaking spirits are consumed with a gusto that turns to horror when the truth of the situation emerges."