I know, I’m breaking the mold by doing a human (who isn’t besotted with a douchebag unicorn), but here’s how this happened.
I was visiting I and M with my mom, and even for a Jew, I’s guilt level is astounding. He can turn literally anything into something to feel bad about, with no pause for air. Finally, when he managed to turn yet another conversation that had nothing to do with anyone being at fault for anything into an ‘Oh, I’m so sorry, it’s all my fault’ through a devious chain of logic that I don’t even pretend to understand I finally said, “Oh my god! I don’t even see you coming and suddenly you’re there! Guilt ninja!”
And then I yelled ‘Guilt ninja’ whenever he did that for the rest of the trip, because that is my job as a younger sibling.
And now there’s a cartoon. And yes, there are several more already. Guilt ninja lurks where you least suspect!