Green’s Dictionary of Slang

pish-posh n.

also pish-tush
[SE pish!, nonsense! rubbish!]

(US) rubbish, nonsense.

[US]G. Bronson-Howard Enemy to Society 314: ‘Oh, pish-tush, Bates!’ returned Canby good-naturedly.
[US]Wash. Herald (DC) 28 Oct. 2/2: Such is the pish-posh on which this comedy is based.
[US]Ogden Standard Examiner (UT) 4 June 4/1: Theater-goers have been treated to an unparalleled assortment of theatrical pish-posh and rot.
[US]C. Himes ‘Prison Mass’ in Coll. Stories (1990) 160: Signifier’s lips curled in a sneer. Just a lot of pish-posh, all of it.