Making noise in the blogosphere with beer.
I didn't know about the hydraulic sandwiches wich is probably a quite recent joke. When did you hear about liquid bread? Could you ask around yourself about that curious thing? Who begun with that analogy?
I don't know when the term "liquid bread" originated, but people throughout history have often used bread as a meal staple. Monasteries were known particularly well for this (http://www.beerhunter.com/documents/19133-000107.html). In many countries wine or beer was served as PART of a meal (like potatoes or carrots), not just to wash it down. Course, this was also partly because water wasn't exactly available at the tap as we have it now.
Again, don't know who started it, but the term does have some historically sounds roots.