A Riddikulusly Difficult Harry Potter Quiz. Do you know which King’s court Nearly Headless Nick served under? Well, I do, and I'll quiz you with some Riddikulusly difficult (perhaps even impossible) Potter-themed questions. Of course, the books are better than the movies, so you moviegoers might want to brush up a bit. This is very, very difficult. Consider yourself warned. (p.s. - it's one of the Henry's).