Hang your magic mirror on the wall, turn around so the back of your head appears in it, then say three times, "Cillian Murphy and me are friends, but he's kind of a liar."
Then poof! Cillian Murphy will call you up and tell you how glad he is to talk to you, his old buddy. You'll tell him you're glad to talk to him too, then he'll say that he just found out he's related to Bill Clinton.
"Not like first cousins or anything, but we do share an ancestry," he'll say.
You won't challenge him, because really, how do you challenge something like that? And seeing as he's already a movie star, why would he feel the need to lie about being related to Bill Clinton? All the same, you don't really believe Cillian Murphy, and it makes it hard to be friends with him even though you only just became friends thanks to your magic mirror.
The big question: was Cillian Murphy kind of a liar before you bought the magic mirror, or did you make him into a liar when you intoned your spell before the magic mirror's reflection?
The even bigger question: Why doesn't your magic mirror do anything else?
Happy Magic Mirror Day!