Green’s Dictionary of Slang

1. (US prison) pornographic.

1967		M. Braly On the Yard (1977) 130: These were...hotdog books heavy with sex.
1975		J. Carr Bad (1995) 115: The homo convinced him to bring in Playboy and every other hot-dog magazine imaginable.

2. (US) homosexual.

1975

J. Carr Bad (1995) 44: I’d known and lot of hot-dog guys before [...] but never had I seen the likes of Maynard Farrell. Maynard was the doggie daddy, master of the homos.