Green’s Dictionary of Slang

1. a general superlative.

1961		R. Gover One Hundred Dollar Misunderstanding 133: An she don’ sit there wiff no hotass grin on her face neither.
1993		R. Shell Iced 214: Kicker had visions of a hot-ass four-piece rock-n-roll band.
2012		M. Lacher On the Bro’d 6: [H]is hot-ass stacked trixie Maryann.

2. see hot-arsed adj.