- “My first material possession! Oh, joy! I can hardly wait to try it!”
- ―Stimpy, upon receiving the litter box for the first time.
Stimpy's Litter Box is, as its name suggests, his litter box. He first received it in "Big House Blues" from the family that adopted him and Ren. As a result he values it highly, becoming very distraught when it is destroyed or broken.
The litter box oftentimes changes depending on the episode. In majority of episodes, it is red, while in others, it is blue. In "Fire Dogs" it had wheels and a handle attached to it like a wagon. In some episodes, it may have the word 'Stimpy's' on it or 'litter box' on it. According to "Stimpy's Big Day" Stimpy fills the litter box with Gritty Kitty Litter.
The litter box makes its first appearance in "Big House Blues" as a gift for Stimpy. After they are adopted by a Little Girl and her family, Ren and Stimpy each get gifts from her mother, Ren's being a sweater and Stimpy's being his litter box. As he and Ren were in poverty prior to this, Stimpy gratefully hails the box as his 'first material possession' and embraces it, in the process pulling Ren into it, much to his dismay.
Stimpy is shown using it as a chair in "Stimpy's Big Day" when he is watching The Muddy Muddskipper Show. He also squishes the litter between his toes when he sees a Gritty Kitty commercial. After several agents come to give Stimpy his prizes for winning the contest, among them $47 million, Ren attempts to prove that he was the one who wrote the poem, among the ways he tries being eating the cat litter to prove how much he loves it.
In "The Big Shot!" Ren sadly finds Stimpy's litter box as mementos he left behind. Stimpy also didn't bring the litter box with him to LA as he is never shown using it.
In "Fire Dogs" Ren and Stimpy are once again poor and wandering the streets, with Stimpy carrying his litter box with him as a wagon. After Ren complains of his hunger, Stimpy offers him a crumb, which the latter gratefully eats. After Ren asks what it was, Stimpy reveals that it was his last grain of litter. Angered, Ren hits Stimpy over the head with the litter box and breaks it, much to Stimpy's dismay.
In "Stimpy's Invention" Ren finds the filthy litter box under the influence of the Happy Helmet and because of the helmet's forced glee, is forced to clean it. As he begins to scoop it out, he slowly loses sanity, laughing wildly.
In "Sven Hoek" Sven finds Stimpy in the litter box during a game of 'seek-and-hide' and becomes fascinated with it, asking Stimpy if he can have some of the litter, to which he agrees. Sven hops in with Stimpy and the two shut the closet door and start to play Circus, using the litter as props.
The litter box makes a cameo appearance in "My Shiny Friend" on the pair's lawn. Like Fire Dogs, the litter box is shown as a wagon.
In "Ren's Bitter Half" Evil Ren steals Stimpy's litter box after he and Indifferent Ren go on a walk. When they get back, they find Evil Ren throwing several of Stimpy's possessions into a vat of acid, among them his catnip mouse, Mousey, his favorite record, Happy Happy Joy Joy, and finally his litter box. Evil Ren begins to sadistically toy with Stimpy by holding his litter box over the vat and threatening to throw it in. After Evil Ren does so, Stimpy faints.
In "Ren's Pecs" Ren is bullied by a large muscle man who kicked litter on to Ren's face from Stimpy's litter box