Interesting term, this one. Anu writes that it's often applied to soldiers.

I remember having read the term years ago--probably when I was a little girl, which would put it over four decades ago--but do not remember the soldier connection.

I suppose some kind of pun could be employed, too, applying the term to poor, dry sherry. Which one of Shakespeare's characters loved sack so much? It was a Sir Toby Belch kind of character, but not Sir Toby. His name began with an "F"--and I'm drawing a blank here. Oh, Falstaff! That's it! Falstaff and his sack!

Bard regards,
WW