yeah our gran used to do the same thing with us i picked up the term from her and it is pretty sentimental to me as we were very close ill keep on using it in the manner that i have always used it and not pander to a group of people who want to be offended by it our gran was pretty dark skinned as was our mum and as are the seven of us to varying degrees when we asked her why she and mum were dark and grandpa and dad werent her response was there was a nigger in the woodpile so yeah you might be onto something with the nigger knives but still i loved my gran and miss her terribly every time i call someone a porch monkey it reminds me of her