Warned for. Using the word slope. So.? Can't we use the expression slippery slope any more ???

I remember. Singing along with Paul Robson as a child to a record .
"Four little ???????s lying the bed three was sick and the other was dead, sent for the doctor the doctor said, feed the ??????? On shortening bread.
Imagine today him singing this, or any one else ( he sang it inspite of the fact he was as black as the ace of spades.) oops!
No it isn't a nice word, however it's one used by the ignorant negro's themselves when upset by one of their country fellow men and women and by stupid racist people who should know better.
As they refer to whites as "White Trash and Honkeys."
No one would use these expressions other than the ignorant, however we also cannot use the word coloured I believe.
We have the word Negro, is that acceptable.?