What's the same between Alice and black people When you put them in chains they start singing
Are you making a joke about people in chains?
It's just a pun on Lewis Carroll's book. You see, 'racist' here and 'slatist' there, you get it?
Slavery is an awful part of our history and affects people even today. Making jokes about them being in chains can be hurtful. You should consider learning more about black history from books so that you can understand why those jokes can be hurtful.