The Butterfly

A Kipper and Pig duet primarily set in The Park, in which Kipper pursues a butterfly, and eventually realizing that it is drawn to purple objects, succeeds in capturing it, only to realize that he has done it a disservice and frees it.  This episode is remarkable for the presence of a human baby, the only moment I'm aware of in the entire series that humans make an appearance.

Kipper does not do particularly well by the child, accidentally popping its purple balloon while reaching for the butterfly and then slinking off before any.  The central act has Kipper back at home experimenting with color mixing until he happens on the correct combination for making purple.  Kipper uses his new found knowledge to construct a purple hat that he's places on Pig's head, and then succeeds on snatching the butterfly after it lands there.  He sends  Pig to fetch a jam jar from Kipper's house to put the butterfly in, but once it is imprisoned Kipper notes "You're not very happy, are you" and releases it.