If you are having trouble understanding simply replace cis white male, with any other group like gay black woman. Is it still funny and ok?
I don’t like to discriminate against races and sexes no matter where it’s coming from. And saying “it’s just a prank, bro” doesn’t make it ok.
There are plenty of ways to make a joke like this by actually targeting bigots.
My simple rule is: if it’s something you are born with it’s not ok to lump people together (race, sex, sexual orientation). If it’s something you chose, like political affiliation, etc then it’s all fair game.