Scientists Uniqua and Pablo create a growth formula, but the lab Worman accidentally gets sprayed. Uniqua gets Groundskeeper Tyrone to help her catch Sherman while Pablo tries to create a shrink formula, but makes a pink formula and a stink formula before he can make an incredible shrink formula.
Uniqua and Pablo are in the backyard wearing goggles. They introduce themselves to the viewer as scientists Uniqua and Pablo. They sing I'm a Scientist as they explain what formulas and potions they have created. They also discuss what potions they are working on.
The backyard transforms into a college's park. They attempt to get to their lab by running across the grass, but Groundskeeper Tyrone stops them and tells them that they cannot cross the grass and points to a sign posted in the ground labeled "Do Not Walk on the Grass". They accept and walk around the grass. They enter the laboratory and begin trying to make a growth formula as they sing Mix it Up. They succeed in their project and test the potion on some popcorn. The snack food grows larger and larger. The scientists congratulate themselves and leave the lab. The duo's lab Worman, Sherman, squirms out of his tank to eat some popcorn.
Sherman devours the food, causing him to grow slightly bigger. He eats more and more as he gets bigger and bigger. The Worman giggles as the scientists return to their laboratory. Uniqua and Pablo gasp as they watch Sherman grow and later escape from the lab. Uniqua exits the building and tells Pablo to create a shrink formula. Uniqua alerts Groundskeeper Tyrone about the rapidly growing lab Worman. Tyrone agrees to help Uniqua find Sherman while Pablo makes a shrinking potion. They sing Where'd It Go? as they search for Sherman while he hides from them. Pablo rushes outside with a beaker of formula.
Uniqua pours it into her spray bottle and squirts it at Sherman. Sherman's coloring turns from yellow to pink. Uniqua's face reddens as she scolds Pablo for creating a pink formula rather than a shrink formula. Pablo returns to the lab as Tyrone and Uniqua try to find the now pink Worman. Pablo pours various potions in another beaker, hoping that it will turn into a shrink formula. A green liquid appears in the beaker.
Pablo gulps as he fears that another mishap will happen. The blue penguin runs outside in search of Uniqua and Tyrone. He finds the two and hands Uniqua the potion. Uniqua spills the pink formula and adds the new formula into her spray bottle. She squirts Sherman with the liquid as stinking lines start fuming from his head. Uniqua scolds Pablo once again for creating a stink formula rather than a shrink formula. Pablo runs back inside the laboratory. Pablo mixes the last few potions into the last empty beaker. He runs outside, only to hear that Sherman will not listen to Uniqua or Tyrone, causing him to disobey them when they tell him to stand still.
Pablo then gets an idea: lure Sherman over with his favorite food, popcorn. Tyrone uses his crane machine to drop giant popcorn kernels on the ground. Sherman catches a whiff of the delicious food and squirms over. He eats the popcorn as Uniqua sprays him with the final formula. Sherman changes from stinky, pink, and huge from pleasant-smelling, yellow, and small. Uniqua, Pablo, and Tyrone all give huge sighs of relief.
Pablo's stomach rumbles. Uniqua asks him if the sound is another giant Worman, but Pablo assures her that it is just his stomach. He invites the two over for more popcorn. The others accept as the college transforms back into the backyard. The children sing the end song and enter Pablo's blue house. Pablo and Uniqua open the previously closed door. Pablo shouts "I made a..." "...shrink formula!" Pablo and Uniqua shout together. The end credits for the episode start.