There is an un-aired episode of Dexter’s Lab meant only for adults!

The episode is only supposed to be aired on conventions, like The Los Angeles Comic Book and Science Fiction Convention and not aired on TV. In the episode, Dexter feels that DeeDee’s rudeness is becoming a restriction, so he made a device for her that renders her polite and charming. The device messes up and DeeDee is separated into a polite half and a rude half.

The reason this is banned from airing in TV is because the episode contains multiple swear words, Dexter moons the audience, and flicks people off, including, at one point, telling DeeDee that “this s#!t is f*cking great!”

(Source)