Green’s Dictionary of Slang

high tone v.

[high-tone adj.]

(US) to snub, to ignore.

[US]J.M. Grider War Birds (1926) 35: He got hightoned by the Colonel and [...] indulged himself in an orgy of bootlicking.
[US]E. Booth Stealing Through Life 69: You have to use their language so they won’t think you’re trying to high-tone them.