Green’s Dictionary of Slang

(orig. US) usu. in ironic use, anyone who sets themselves up as tough, aggressive.

1970		D. Ponicsan Last Detail 74: But, lad, you’re talking to the original Billy Bad-Ass. [Ibid.] 7: Billy’s name, of course, is not Bad-Ass [...] Buddusky became Bad-Ass, which in navy parlance means a very tough customer.
1987		(con. 1967) E. Spencer Welcome to Vietnam (1989) 26: I’m hot shit; Billy Joe Bad-Ass himself.
1997		GWAR ‘Billy Bad Ass’ 🎵 Billy Bad Ass / Little Billy Bad Ass / Cause I’m bad – Billy Bad / Bad Bad Billy – Little Billy Badass.
2000		www.bladeforums.com 15 Mar. 🌐 People in Los Angeles get pets for all the wrong reasons (e.g. rottweilers, pit bulls, etc). They’re basically saying, look at me, I’m Billy Joe Bad-ass with this vicious animal on a leash next to me.
2002		Fry-Skimmer ‘That Nickel-Slick Badge (Part 1)’ 🌐 ‘Oh, yeah, you were Billy Bad-ass with your gauge, with your chains, with your badge…’ John took aim with his shotgun. Then he fired.