What is that really weird Simpsons episode...?

Question

Patty and Selma are coming round so Homer hides behind the bookcase, but there's like a hole to another dimension or something behind it, and he gets sucked in.

What's it called?

Answer 1

Sasha May is right I watched that one just the other day

Answer 2

Treehouse of Horror VI is the sixth episode of The Simpsons' seventh season and the sixth episode in the Treehouse of Horror series. It premiered on October 29, 1995, and features three short stories called Attack of the 50-Foot Eyesores, Nightmare on Evergreen Terrace, and Homer³.

I think this is what you are looking for via wikipedia.

edit:Patty and Selma visit the Simpsons to clean a bucket of seashells. While trying to hide from them, Homer looks behind a bookcase and enters an eerie third dimension. Homer explores the peculiar area, being depicted as a 3-D computer-generated animation. Through the walls, he calls Marge for help.