In a 2017 “Ask Me Anything” thread on Reddit, co-creator David X. Cohen was asked about any jokes they wrote that the “higher ups” made them cut. Cohen gave an example of a joke that wasn’t particularly clever or dirty, but which nevertheless got Fox’s attention:
“…where Bender debates against the Professor to legalize robosexual marriage. When the show was edited for syndication and possible earlier broadcast times, the Fox censor would not let Bender say ‘I’m our A in the Hole.'”
You may be thinking, “That’s it?” The line is just a mild play on the phrase “ace in the hole,” with Bender instead referring to himself as an ass that nobody wants to deal with. Although Comedy Central was fine with the line, if you’re watching a rerun on Fox you’ll probably hear Bender call himself “a master debater,” which Cohen said “was deemed acceptable.”
It’s a bizarre change, because a pun about masturbation seems more inappropriate than the original line. But the Fox censors work in mysterious ways, as multiple Matt Groening-created shows have mocked over the years. Their most potent critique was probably the opening to a “Treehouse of Horror” episode in “The Simpsons,” where a Fox censor is shown crossing out all the jokes in the script for the episode, even the jokes he finds funny. The segment ends with the censor being stabbed to death, which should give you a good idea of the writers’ thoughts on their constant meddling.
The good news, as Cohen’s example shows, is that their arbitrary rules are often easy to work around. When they tried to prevent the “Futurama” writers from telling a risqué joke, the writers slipped an even more egregious joke right under their noses.