Poppycock

Picture it; You're at a fancy gala, enjoying the festivities, when you happen to overhear some boisterous braggart announcing to all the world a myriad of fanciful tales the likes of which no sensible person would condone. In order to denounce this charlatan, you wheel about and cry, of course, "poppycock!"

In holding with my fondness for odd and archaic words, poppycock is a fun word that really puts people off balance. However, it's simply a noun that means "Senseless talk: Nonsense"(AHD) A look at it would suggest some obvious etymologies, but intriguingly, the word has absolutely nothing to do with the words it appears to be comprised of.

In reality, poppycock is a portmanteau, but not of what it appears to be. It comes from a Dutch dialectal word pappekak. Pappekak is formed of two seperate words: pap, which comes from the Middle Dutch word pappe, which may be from the Latin word pappa, meaning food, and kak, meaning dung, which comes from the Middle Dutch kacken, which in turn comes from the Latin cacre, both meaning "to defecate". (AHD)

So, while the etymological story for this one is sort of self explanatory, describing it politely is a trial, at best. Perhaps one way to put it is that, as a food, dung is most certainly useless... much like poppycock is useless talk...