There was a song in the 60's or 70's sung by a black comedian in the UK - or at least I think he was a comedian as he had been on lots of TV shows.
The song concerned a boy who went to his father to ask permission to marry a girl. The comedian sung his reply to the boy making out that that the girl was somehow a relation of the boy because the father had been the lover of the girls mother. The boy could not marry the girl because of this.
The song went through various family members and/or the community in this way ending each line with something like: "but your mamma don't know"
Does anyone remember this song and the name of the comedian?