Although it seems that nobody has come up with a name for them that sticks as well as "Karen" does, anyone in a customer-facing role can tell you that male Karens definitely exist and they're as aggressive and entitled as any other problem customer they have to deal with.
And while it's true that any business has roughly the same chance of receiving an angry message from someone who didn't see their unreasonable expectations met, that goes double when you're in a creative field as it's hard to find people who don't undervalue your work at the best of times.
But while interactions with this kind of customer are usually exhausting, it seems that at least one tattoo parlor owner has found a way to get some fun out of them.