Stepping lightly over toenadering, ( nothing to do with toe) which is of current day-to-day use in the Netherlands, I'd like to add some poppy-cock.
I've searched and followed quite a number of lively online guessings on the word ; it all keeps turning around this:

Americanism; perhaps from < Dutch pappekak, equivalent to pappe- + kak excrement. Nothing more defined. In Dutch dictionaries and etymologies the word pappekak is not to found. (so far)

On the other hand, there is Dutch word in traditional and actual use: poppestront - doll's shit. (not exactly the same connotation as poppy-cock but in the same direction). The word kak is still alive but not considered a refined word to use in table conversations like here on this board.