Mergie is a creature who appears in Neat Stuff To Know & To Do, and shows Kai-Lee and P.J. how a puppet can appear to sit on a stool. Mergie explains how the effect is achieved, by installing a mirror in the stool that the puppeteer can hide behind. The mirror shows the reflection of the floor and inside of the stool, creating the illusion that the viewer is looking through it.

This same effect was used with Kermit the Frog for the song "The Magic Store" in The Muppet Movie, and for a duet with Andy Williams on The Muppet Show.

The puppet used for Mergie was recycled from the Blustering Bellowpane Monster and would later be used as Singalotti in Mopatop's Shop.