I remember in the Leo Sayer episode, Leo is up a tree and wild animals like a beaver, a woodpecker, and a bear with a sawfish were trying to chop the tree down. But then Crazy Harry came in and blew up the tree causing it and Leo to fall.
Also, Jean Stapleton asked Kermit if she could perform with her favorite Muppet. Crazy Harry. Harry had his own musical instrument, The Explodaphone. A nervous Kermit introduced them and it showed Jean singing, "Wild About Harry", while Harry was on this huge wall setting off explosives while Jean was dancing and singing wildly to the booms.
Also, when The Muppet Show started airing on the TNT channel for a while. Crazy Harry was kind of the station's mascot, bringing in explosives during the TNT logo.