Green’s Dictionary of Slang

1. an intensified form of what or whatever.

1837		Liverpool Mercury 21 July 8/3: What the h—l would become of the Church if these French Atheists should get the upper hand? if our religion would not go to pot, I’ll be d—d.
1929		E. Dahlberg Bottom Dogs 891: Shrimp was always wondering what the hell fun a fella could have anyhow carrying on with himself like that.
1939		V. Davis Gentlemen of the Broad Arrows 114: You can do what the hell you like.
1939		P. Cheyney Don’t Get Me Wrong (1956) 40: I wonder what the hell is she goin’ to pull now?
1962		R. Cook Crust on its Uppers 38: I can’t remember what the hell I was on about.
1982		D. Evans One Monkey Don’t Stop No Show 38: You can do what the hell you want.
1995		J. Stahl Permanent Midnight 149: I didn’t know what the hell this geek wanted.
1999		Indep. on Sun. Rev. 20 June 21: I don’t know what the hell language you are speaking, buddy.
2008		posting 16 Oct. at Men’s Health (UK) 🌐 Eat what the hell you want, you dont need a six pack in the army.

2. in attrib. use of sense 1.

2010

Codella and Bennett Alphaville (2011) 112: Those winging-it, what-the-hell situations.