Chums

Chums was a television show that the Tenth Doctor sometimes watched with Rose-the-cat.

It had a theme song that contained the lyrics "cause we'll always be chums!"

Its cast of characters included Ross and Russ.

When Rose used a chainsaw to install a cat flap in the TARDIS, one of its unforeseen effects on the fabric of time and space was on the filming of show's final episode in 2014, where the guy who played Russ suddenly turned into a frog. (COMIC: A Rose by Any Other Name)

Behind the scenes
Chums is a reference to the real-life TV Show Friends, which also exists in the DWU.

The concept of a Friends parody by this name is by no means exclusive to this story. A sketch series of the same name ran on ITV's, while a British remake of Friends by the name was mentioned in an episode of.