Funny this topic should come up today, since last night I saw 'bamboozled' written by Spike Lee. It's about a modern day version of a minstrel show set on a watermelon patch as a parody of the stereotypes created by ol' theatrical shows and early television programmes. Lo and/or behold, the name of the sidekick in this programme was Night 'n Day. So yes, coupled with the information above, there seems to be a definite, if abstract link to the disparaging ways in which blacks were light-heartedly dubbed.
It was a really sad film actually. The last 10-15 mins was outakes of various progammes (right up to modern television) where black americans where always the butt of the jokes, or just saying 'Yes sir' or 'No sir'.