BLACK SABBATH lyrics - "Blow On A Jug"

Blow on a Jug
Everybody come on - blow on a jug
Be like me and blow on a jug
I want you to blow on a jug
Everybody begin - blow on a jug

If that's the sort of jugs you are talking about, then you are in reference to a bit of crockery that might have had an ever-diminishing amount of whiskey in it. Blowing in it just right produces a pleasant, rythmic bass line accompaniment to bouncy bluegrass, country, or "jug band" music.