Remus Lupin

Well, first I want to make sure it won't give her the collywobbles.

But then, we'll have to try it on her in circumstances where she might actually try telling someone the dog is really named Sirius, or whatever else we're prohibiting her from saying. Or doing, come to that.

So eventually we'll have to create those circumstances, encourage her to tell the very thing we don't want her to tell, and then let her feel punished for doing what we've asked.