You know the saying: "once you go black," You're a single parent.
What are you trying to say about black people with this joke?
Just a joke to make fun of the people of colour.
It may be a joke, but jokes like that perpetuate racist stereotypes about black people. Joking that black people abandon their kids is harmful and offensive. You should think about you would feel if someone said you were a bad parent based on the color of your skin.