Okay, we know that "Rugrats" made Nickelodeon a success, and it was one of the biggest kids shows of the 90s, but that doesn't mean that it didn't have it's fair share of censorship, and these are a few episodes that never got made, but the episode plots were thought of, during the early '90s!
1-- Tommy The Sage
Apparently, this episode was to have Tommy give words of wisdom to his fellow Rugrats. Nick disapproved of this episode, as it did not seem fit for the series, especially in a flashback sequence.
2-- Didi's Cold
This episode was to have Didi come down with a cold, and probably explain how it would affect the other Rugrats. It was eventually rejected.
3-- Metamorphosis
Rejected by K-C due to its fantasy sequences, though it might've been done later on as Chuckerfly.
4-- Chuckie Gets Trapped
This episode was to have dealt with Chuckie getting his head stuck in the bannister (those small poles that hold up the handrails on the stairs). This was rejected by Arlene Klasky, as she felt that it presented a danger issue.
5-- Dog Show
Originally rejected, as K-C did not more than one episode centering around Spike this season. It was never made.
6-- Rear Crib Slat
Rejected, as Nick didn't think the story concept would work.
7-- Tommy The Gambler
You got to know wnen to hold'em, know when to fold'em -- This story was to have taken place at a racetrack, where one or more of the adults would gamble on a horserace. Klasky-Csupo themselves rejected this one not because of the gambling issue, but it was difficult to animate crowd scenes.
8-- The Seance
The Rugrats and/or the grown-ups would've been contacting spirits. Rejected.
9-- The Parade
Rejected by K-C, also due to crowd problems in animation.
10 -- Angelica Takes A Candy Bar (a.k.a. Shoplifting)
Apparently, this episode was to have made Angelica criminally evil, as, as the title implies, she steals a candy bar from a local store. Nick rejected this episode.
11 -- The Case of the Missing Eggs
This might have been the Rugrats' Easter special, as it had something to do with eggs. K-C rejected this one for two reasons; they already have a mystery, The Case Of The Missing Rugrat, slated for that season; and there were too many difficulties in terms of realism.
12 -- Poindexter
Rejected, as it was already used in The Last Babysitter, which was initially rejected by Nick.
13 -- Client Dinner
Not sure if this is a rejected episode, of if this is an early title for Waiter, There's A Baby In My Soup, Dummi Bear Dinner Disaster, or even Miss Manners.
14 -- Glasberg's Polynesian Restaurant
Rejected by Nick, as the setting was too similar to Client Dinner (above). By the way, the "Glasberg" in the name referred to Gary Glasberg, who had written one episode that did make it to air in the 2nd season -- The Dog Broomer.
15 -- Chuckie & Susie (?)
This episode was listed in the schedule, but later omitted for unknown reasons.