Tree House of Horror VI - S7-E6
Trivia: In the story where Homer get transported to the 3rd dimension there is a string of hexadecimal numbers floating in space. The string reads: %46%72%69%6E%6B%20%72%75%6C%65%73%21. If you paste these into your browser address bar you can see that these convert to say 'Frink rules!'