"Two african american kids (a" joke

Two african american kids (a boy and a girl) go out trick or treating and
stop at a lady's house for candy.
Lady: Who are you two supposed to be?
Kids: Hansel and Gretel
Lady: You can't be Hansel and Gretel, they're white.
So the kids went home and changed and went back to the lady's house.
Lady: Now who are you supposed to be?
Kids: Jack and Jill.
Lady: You can't be Jack and Jill, they're white.
Then the kids went home to change again but went back to the lady's house
with nothing on this time.
Lady: What are you supposed to be this time?
Kids: Hershey bars, one with nuts and one without.