Nigger in the woodpile American old-fashioned noun phrase
The word "woodpile" could be replaced by the word "fence."
Used for saying that there is something suspicious or wrong
When I arrived they stopped talking and stared at me. I guess there must be a nigger in the woodpile.
To have no faith or confidence in something
To be extremely skeptical of someone
Used to indicate a dubious, suspicious, or potentially immoral or illegal past history.
If you describe someone as shifty-looking, they seem dishonest, untrustworthy, or suspicious.
To distrust someone.
This phrase dates back to the 1840s and 1850s when the Underground Railroad was at its peak. The phrase is thought to have originated from actual cases of escaped slaves being hidden behind piles of firewood during their journey north.
Another possible source for the phrase is the practice of transporting pulpwood on special railroad carts with an exterior frame and the wood packed within in quite neat rows and stacks. It was possible to smuggle people into the pile itself due to the nature of the cars.