Green’s Dictionary of Slang

what-the-hell adj.

[what the hell! excl. (1)]

incomprehending, resigned, weary.

[US]B. Stiles Serenade to the Big Bird 60: She had a sort of what-the-hell look on her face.
[US]L. Block ‘Murder Is My Business’ in One Night Stands (2008) 117: And they [i.e. prostitutes] walk with a what–the–hell shuffle.