Green’s Dictionary of Slang

pfft adj.

(orig. US) finished, terminated, over.

1928		W. Winchell Your Broadway & Mine 29 Nov. [synd. col.] Jack Miye and Phox Philms have phffft!
1938		W. Winchell On Broadway 16 Mar. [synd. col.] The Glen McNaughtens [...] and his frau have pooffft.
1950		R. Starnes And When She Was Bad 80: ‘Here is this gal. She has round heels. And here is this screwy artist. [...] He doesn’t like her laying all hands. So, pfft.’ He drew a finger across his Adam's apple.

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