Jim,

In the UK (and assume Ireland, thanks to a shared history), bullshit does actually have more historical roots, but, it seems that it refers to "physical" nonsense rather than verbal. "Bullshit" as far as the military were concerned, was the apparently pointless cleaning, polishing or the "time wasting" jobs found for squaddies and matelots (do these terms count as idioms?), my late father (called up in July 1939)used, occasionally, when engaged in the odd boring job, be heard to sing a ditty including the lines:
"... How green is my Blanco,
How sqare is my kit
That's how we win wars
With all this bullshit..."
(I regret that I never learned the song). Bullshit was usually shortened to the more socially acceptable "bull" (indeed, in some places, giving something that extra - often not strictly necessary - clean/polish is still called "bulling")

Good luck.

Walrus