No, it’s not Linda Tripp. It’s Christine O’Donnell, denying she is a witch, and asserting that she is you:
Embedding the Monty Python bit feels like too much of a cliche. So what do you think? I just have one question: the white smoke behind the woman in the black dress . . . that’s not coming from a cauldron, is it?
UPDATE: For an “I’m not a witch” clip that is slightly less hackneyed than the Python bit above, enjoy this bit from the Princess Bride. The key line is at 3:09.