Why would you even do this. What is there to make fun of? Police violence against minority groups isn't funny.
Because many people are shitty!
In a town I used to live in here in Denmark, about 10 years ago, just when Facebook had gotten traction; we had a case with a group of teens who walked past a "weird" looking man who was walking his dog on their way home from school. They decided to follow him to his house.
They then started pranking him- They took photos of his house, wrote down his address and made a facebook group to watch out for this man saying he was a pedophile- Within a couple of weeks tens of thousands of signatures had been collected and the man was eventually picked up by the police for questioning, but not before being fired from his job.
When the police came to the realization that there was no accusation, no victim or anything, they eventually traced the facebook group back to the teenagers who started the prank, and it turned out- when the kids where asked why they would make up a story like this, that they just thought it would be funny.
I get scared when I see how easy it is to take a photo someone, make a vague offensive caption and then putting it online, with a vast amount of people who will take it at face value.
But I guess the opposite is plauseable as well. "it was just a ghost costume lol. we are not really kkk". I can see how a Cartman-ish defense could be hurdled out. It's a potential mess no matter how you deal with it!