While Dana Barrett was attempting to give her child Oscar a bath, she turned on the taps and started running bath water. While her back was turned and she began undressing Oscar, the water changed and the Psychomagnotheric Slime began brewing into the bath. It then rose as a huge, pink blob and lunged for Oscar. In a panic, Dana fled with her baby and headed over to Peter's apartment. Egon Spengler and Ray Stantz investigated the bathroom and only found some slime residue.
Behind the Scenes
The Slime in the Bathtub went through several concepts. While trying to figure out what would kidnap Oscar from Peter's apartment, the concept of the tub came up.  Initially, the tub was going to turn into a porcelain version of Audrey II from "Little Shop of Horrors." Then it would turn into the beginning of an endless road then a bubble bath monster. Dana Barrett would put bubble bath in the tub and turn her back. The bubble bath would rise up to tower over Dana and the eyes of a dark shape within it open up. The lensing effect used would make all the bubbles look like eyes, too. Dana would panic and throw a hairdryer into the tub. The electricity would disperse the bubbles then the two eyes would crumble into cinders and disappear down the drain. Ultimately, it became just slime that fills the tub and the slime rises up, prompting Dana to run. Ivan Reitman decided the slime should turn into a creature inside the tub. 
A tub was made out of white silicone to look like it was porcelain and so it could bend. The tub creature was made out of dielectric gel - a Dow Corning breast implant material - reinforced with china silk and spandex. The slime creature would be operated like a hand puppet. Tom Floutz put his arm up through the bottom of the tub and operate the creature. The slime was dumped on the creature. Floutz had to endure and let the slime pour down on him, too. A maw-shaped piece of fiberglass was placed inside the puppet and attached to a vacuum tub in order to simulate a mouth. The tub and slime creature were filmed against a bluescreen. There wasn't enough of a pay off so John Van Vliet of Available Light did a cel animation of an animated tongue for the last shot for about 25 frames. 
- ↑ Eisenberg, Adam (November 1989). Ghostbusters Revisited, Cinefex magazine #40, page 29. Cinefex, USA.
- ↑ Eisenberg, Adam (November 1989). Ghostbusters Revisited, Cinefex magazine #40, page 22-23. Cinefex, USA.
- ↑ Eisenberg, Adam (November 1989). Ghostbusters Revisited, Cinefex magazine #40, page 21 footnote, 23. Cinefex, USA.