that ain't no lie

that ain't no lie

A very informal way of emphasizing that something that was just said is the truth. A: "We're gonna get in some serious trouble if we get caught." B: "That ain't no lie—so let's not get caught!" All this legal stuff at work has me really stressed out, and that ain't no lie.
See also: lie, no, that
Farlex Dictionary of Idioms.

That ain't no lie.

Rur. What was said is true. (The highly informal word ain't is built into the expression.) Tom: Sure is hot today. Jane: That ain't no lie. I'm plumb exhausted, and that ain't no lie.
See also: lie, no, that
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • glom
  • glom (someone or something)
  • glommed
  • after meat, mustard
  • how-d'ye-do
  • flow
  • I tell you
  • bottle
  • card
  • carded