Gunk is constantly introducing dangerous Flyspeck Island flora and fauna around Curtis for the express purpose of causing Curtis physical and mental harm for his own amusement. And since he knows Curtis is, frankly, rock stupid, he knows he can do it as much as he likes and Curtis will never catch on. The only one Curtis seems to remember is the Flyspeck Island Chameleon - and that's because it tends to get him in trouble with his parents.