Jack is about to trudge up the hill, but forgets who he needs to bring along with him. All he remembers is that their name rhymes with "hill." Mervin offers his services, even reciting a bit of how their new nursery rhyme would go. However, Jack and Kermit turn him away, pointing out his name doesn't rhyme. When Jill declines going up the hill anymore, Jack asks around for a new partner. Mervin re-appears, now deciding he won't go up, not having realized about the "tumbling after" part, leaving Kermit as Jack's unwitting partner.
Mervin is also the name of one of the Merggles, also played by Jerry Nelson.