/ ˈsəʊ ən səʊ; NAmE ˈsoʊ ən soʊ/ noun ( pl. so-and-sos ) ( informal )
1.
[ usually sing. ] used to refer to a person, thing, etc. when you do not know their name or when you are talking in a general way :
What would you say to Mrs So-and-so who has called to complain about a noisy neighbour?
2.
an annoying or unpleasant person. People sometimes say so-and-so to avoid using an offensive word :
He's an ungrateful so-and-so.