Hamster
From Tardis Wiki, the free Doctor Who reference
Hamsters were Earth mammals often kept by humans as pets. Dougal Dunnock owned one, which he tried to breed with Mervin the Missing Link. (PROSE:The Last Dodo)
In her youth, Ace was the "hamster monitor" in the classroom run by Miss Marshall. (PROSE: Legacy) The Fourth Doctor once reproached K9 for his slow progress in cutting through a wall with his laser by saying that "a hamster with a blunt penknife" could do it more quickly. (TV: The Androids of Tara)