Q:

"Spit and baling wire"

I just heard the phrase: "spit and baling wire". I cannot find it anywhere—can you help give me a reference, the origin...and the meaning? 

A:

It means something cobbled together or a makeshift solution. For example: 

My old car is so old and broken down, it only gets by held together with spit and baling wire.

Baling wire is wire used to hold together bales of hay. Little pieces of hay often fall off bales, as baling wire cannot keep every little piece of hay together. And of course, spit doesn't really hold much of anything together. I hope that conveys the makeshift nature of the idiom.

A:

Origins of this (and similar) phrase(s) may be a bit murky, but are generally associated with farming and the introduction of compactor-style baling machinery that produces rectangular bales (the most common type of hay bale prior to the introduction of the far larger round bale).  In American farming on the south-central plains (Oklahoma, Kansas, Texas), the McCormick baler is often considered the standard, producing a standard bale between 35 and 90 pounds in weight (depending upon the type of hay:  prairie at the lower end of the scale, alfalfa at the upper) with rough dimensions of a little under 2 feet height, 2 feet width, and 4 feet length.
For one cultural reference that has become related to the primary question, consider that a "MacGuyvered" solution is usually achieved by the use of spit and baling wire -- heavy on the spit.
There is a comparative quote I remember from my youth which may help reconcile the variations on the theme that include some form of gum or other adhesive:  

Anyone can succeed with bubble gum [chewing gum] and baling wire. 
  That's for amateurs!  The true professional succeeds with SPIT and
  baling wire.

