Green’s Dictionary of Slang

posh n.3

[SE piffle + tosh n.3 ]

nonsense, rubbish.

[Ind]P.C. Wren Dew & Mildew 270: ‘That’s all tosh and posh’.
[US]Kerouac On the Road (The Orig. Scroll) (2007) 151: You’re talking absolute bullshit and Wolfean romantic posh.