Sluggerlug

From Tardis Wiki, the free Doctor Who reference

The sluggerlug was a creature with a segmented or armoured tail. It lived between a million and one hundred thousand years away from the Vardons. (COMIC: The Forgotten)

The sluggerlug was the origin of "two shakes of a sluggerlug's tail", a phrase which the Third Doctor used occasionally. (PROSE: Island of Death)