The Abomination (1986)

How bad is it? It's one of the all-time worst.
Should you see it? Yes, though it's gonna hurt.

This is an unheralded piece of great garbage, shot on videotape. The three minutes before the credits roll show everything you're going to see, with a waking-up-from-a-nightmare shot repeated dozens of times, all with a terrible synthesizer soundtrack. If you survive this, you'll enjoy the film.

 A sick woman is watching a televangelist, then coughs up a tumor and is well. While sleeping, her son eats the tumor! It reproduces and grows and is soon filling the house, with the son finding new victims to feed the monster. Parts of the monster come up out of really unlikely places, which is most of the fun of the film, along with the H. R. Pufnstuf/Little Shop of Horrors monster.

Nothing really makes sense and the film doesn't appear to have a resolution until the final credits roll and all is revealed (or is it?), both improving and ruining the film at the same time.