The Repeel of Planet Grimthon
Four light years from Planet Clon is a planet called Earth which, as Enthel discovers, is in the grip of zibb which leads them to believe that a hostile invasion of Planet Clon would be a great idea.
They also believe that using the Planet Grimthon as a staging post for said invasion would be a smart move, as it is half way between the two planets.
Unfortunately Planet Grimthon exhibits the Drag Effect which no one from Planet Earth can survive.
Enthel manages it but only just and, in any case, he is not from Planet Earth. He is from Planet Clon. He is only visitting Planet Earth to take advantage of the healing properties of the River Tyne and has to stop off at Planet Grimthon on his way home to avoid a meteor shower.
So out of common decency, the people of Planet Clon repeel Planet Grimthon because that's the kind of people they are