It's Gumba's birthday! Gumby buys his mom a plant and swings by Professor Kapp's place to give it a ride in his centrifuge to make it grow better. He decides to ride too, just for fun. Unfortunately, the bumbling professor gives him 10 G's instead of 3, and he's horribly flattened. Gumby shrugs off the episode and gives the plant to his mother, who plants it in the front yard. The next day, foliage covers Gumby's entire house, trapping the family inside. Gumby's folks instantly assume it's their son's fault and force him and Professor Kapp to cut it all off.
Thomas Pitz, one of Gumby's classmates, has been truant for several days in a row. One day, the teacher is attacked by an Astrobot. Suddenly, it all makes sense; Thomas Pitz has taken over the Astrobot collective and he's using them to try and destroy school! Gumby, Prickle, Goo, and Professor Kapp capture an Astrobot ship and use it to return to the Astrobot home planet. Gumby makes quick work of Tom's Astrobot guards with his fire extinguisher and drags the little Darth Vader wannabe back home without a shred of dignity to get a firm spanking for his rampant megalomaniacing.
Granny gets cheated out of yet another life savings by the dastardly Blockheads, who trick her into thinking they've made her younger by spray painting her hair and removing the lenses from her glasses so she can't see her wrinkles. There's some more "hilarious" blind Granny driving, and Granny visits her loving family, only to find out she's been cheated. However, she's in luck; it seems Professor Kapp has discovered the fountain of youth (or, more precisely, the flashing light thingy of youth) and he offers to make her 37 years old again. Minga, the meddling little girl that she is, reprograms the machine to make her 7 years old. Kapp refuses to notice the new computer display and next thing we know, Granny's a little girl. To complicate matters, the Blockheads steal the machine so they can use it at their youthful boutique. Gumby realizes something is amiss when people walk into the boutique and come out 7 years old (seems they didn't know how to reprogram it), and a stop is put to them. Granny decides that being old and withered and frail is the life for her and returns to her normal age.