Green’s Dictionary of Slang

(orig. US) snobbish, stuck up.

1922		DN V 147: High hatty—conceited, aloof, exclusive.
1931		R. Le Moyne Barrett A Yankee in Patagonia 145: That high-hatted bookkeeper of Monroe’s had not learned poker at Oxford.
1971		J. Mandelkau Buttons 84: The local pig sheriff stormed in and got all high hatted and hotted up about us being there.