Urectum

Urectum (formerly Uranus) is a gas giant in the solar system. The planet's former name, Uranus, was often of the cause of much laughter in the immature English speaking world, where its name could be interpreted as "your anus". However, by 2620, scientists finally got tired of that "stupid joke", so they renamed Uranus to Urectum, believing the name change to be much less funnier.

Production
The planet of Urectum has never actually been visited during the course of the series, and after its mention in "A Big Piece of Garbage", it has never been mentioned again, as it cannot be used as a joke, due to its renaming. It did, however, briefly appear in "In-A-Gadda-Da-Leela", in a hologram of the solar system.

Quotes
Fry: Oh, man, this is great! Hey, as long as you don't make me smell Uranus.

[He laughs.]

Leela: I don't get it.

Farnsworth: I'm sorry, Fry, but astronomers renamed Uranus in 2620 to end that stupid joke once and for all..

Fry: Oh. What's it called now?

Farnsworth: Urectum.

Trivia

 * The effort to change the planets name was futile, as the Uranus joke could still be made, since "rectum" is synonymous with "anus"