During Grubhog Day, Sprig has to decide whether to uphold his responsibilities or have fun at the carnival.
It is Grubhog day, the annual festival where everyone takes off from work and celebrates the grubhog, a small pig like grub that predicts the weather when it sees its shadow. Anne, Sprig and Polly are excited to try out the rides when Hop Pop appears to tell Sprig that he had him volunteer to watch over the grubhog after the previous one chosen to watch over "caught the plague". The Plantars have not watched over the grubhog due to one of their ancestors eating it, which resulted in him being shunned by the family. Sprig reluctantly agrees even though that means he will have to miss the entire fair. Sprig is forced to wear a suit and hat and given a scroll congratulating him, but adding "DON'T PULL A PLANTAR", Hop Pop and Polly leave, leaving Spirg to sulk with Anne.
As Sprig laments his inability to leave the grubhog unattended to, Anne suggests that they go on the rides with the grubhog in tow so that Sprig will technically be watching it. Together they go on numerous rides while avoiding Hop Pop and Polly. While riding a roller coaster, a misplaced nail causes the grubhog to be launched from the cart and land on the tracks. When Anne and Sprig come back around to get him, a buzzard flies off with the grubhog, scaring the two. They discover a socks and buttons stand and recreate the grubhog as a puppet to use just in time for the ceremony.
The ceremony, surprisingly, goes off without a hitch until they have to cut open the grubhog to examine its liver. Sprig stops the execution and reveals that he lost the grubhog and that he just wanted to make Hop Pop proud of him. Hop Pop apologizes as he realized that he unintentionally put a lot on Sprig shoulders. However, the town is upset that they do not have a grubhog to complete the ceremony, but that they did enjoy the puppets. Anne and Sprig start putting on shows nightly, redeeming the Plantar family name. Meanwhile, the grubhog is revealed to be in league with the buzzard as they fly off "to war".
- Brenda Song as Anne Boonchuy
- Justin Felbinger as Sprig Plantar
- Bill Farmer as Hop Pop Plantar
- Amanda Leighton as Polly Plantar
- Stephen Root as Mayor Toadstool
- Grubhog day is, of course, based on Groundhog Day, minus the killing of the hog.