littledetective:

“Try me,” it wasn’t as if he could beat the
   whole ‘I was given a pill and forced to
   shrink’ thing. Oh, but he was wrong.
   There was an even worse answer than
   that, and one that took Conan completely
   by surprised. Twitching and clenching
   his fists, he felt his aggravation flare.

“Idiot, magic isn’t real!”

“You aren’t the one who’s been on the bad side of a witch using voodoo to give you internal bleeding and trapped you in a magic circle.”

Oh yes, just say that so casually, totally believable. Though to the magician’s credit, nothing in his tone is saying he was joking, and he seems to be completely serious about the absurd response.