Green’s Dictionary of Slang

(US black) isn’t that right.

1967		(con. 1950s) McAleer & Dickson Unit Pride (1981) 239: Ain’t that the truth? Everybody’s got it made but the poor sonofabitchin’ infantryman.
1971		H.E. Roberts Third Ear n.p.: ain’t that it? phrase confirming the factualness of a statement; telling it like is.
1973		J. Yount Trapper’s Last Shot (1974) 115: ‘Ain’t that the truth,’ she said.
1976		C. Keane Hunter 124: ‘Now ain’t that some shit,’ Papa said.
1997–2000		College Sl. Research Project (Cal. State Poly. Uni., Pomona) 🌐 Ain’t dat some shit! (phr.) Has both good and bad connotations, but is usually used as a response to express great awe at something someone else said. [Peabody Conservatory, Baltimore, MD].