How did the phrase "I don't trust him/her as far as I could spit" come to coined to express that one emphatically doesn't trust another?

More Questions. Additional questions in this category.

• 

  The expression some people use when they are in error, "It's my bad." Is it just me, or is anyone else tired of it? :)
  by HEYTHERE on March 14th, 2009 | 2 people like this

• 

  Why do people say 'i dont give a flying fu*k', what does it mean?
  by strange1 still in pb on February 14th, 2009 | 6 people like this

• 

  Where did the express "I'm just saying" originate?
  by bomberpete on May 23rd, 2009 | 3 people like this

• 

  In what situations would you say the following phrase? : “I’ll do you one better!”
  by Running, Fall Up on February 10th, 2009 | 2 people like this

• 

  Have you ever heard the phrase "I'm gonna snatch you bald" what is it's origin?
  by Rocket on May 11th, 2009 | 5 people like this

• More Phrases, I See only professionally researched Phrases, I questions