Of all the people in the world, the Park Keeper is the only one Snufkin really dislikes. In the events portrayed in Moominsummer Madness, Snufkin plants Hattifattener seeds in the park grounds, which sprouts hoardes of hattifatteners. The newborn hattifatteners are highly electric and attracted to the metallic buttons on the Park Keepers jacket, they surround him and causes him to glow in the dark from all of their electricity. The Park Keeper runs away terrified from the park, while Snufkin sneaks in, removes all the signs and proclaims the children to be free. However, contrary to Snufkins plans, the children start following him around instead of going their own directions.
Snufkins assault on the Park Keeper causes great consequences for the rest of the story. Moomintroll, Snorkmaiden and Fillyjonk gets falsely accused of Snufkins crime, and put in jail. Later on, Snufkin admits he's behind it all in front of the Prison Guard, who follow him and the rest of the Moomin family back to the Moominvalley, where they are suddenly surrounded by the Prison Guard and several police men. Snufkin is put before justice and forced to write "IT IS FORBIDDEN" five thousand times over, however he is saved from punishment by the Prison Guards small cousin, who has already written out the phrase the required number of times for Snufkin.