Jerky Jasper is the 1st episode of Uncle Grandpa Season 4, and the 105th episode overall of the series.
Uncle Grandpa tries to meet Pizza Steve's imaginary friend, but when he learns he's not young enough to see him he decides to turn himself into a baby.
Pizza Steve is busy rocking out on his speaker system inside his cardboard box, unaware that he is annoying Mr. Gus with the loud music. His jamming also ends up causing Uncle Grandpa to accidently destroy his rv in a bottle model. Angry he looks for the source of the music and Mr. Gus points him toward Pizza Steve's box. Uncle Grandpa enters his friend's room and instead of telling the truth Pizza Steve lies and tells him that the music was his imaginary friend Jerky Jasper's fault, which he instantly believes.
Uncle Grandpa then pesters Pizza Steve about wanting to meet Jerky Jasper. He tells him that he can't because he has to be physically young in order to see his imaginary friend. Uncle Grandpa then reaches inside belly bag and turns the hands back a little on his biological clock physically regressing him back into a fifteen year old teenager. His teenage self quickly gets on Pizza Steve's nerves and he tells him that he's still not young enough. He then storms off after telling him to stop being such a baby about it. Hearing the word "baby" Uncle Grandpa gets an idea and reaches back inside belly bag to turn the clock hands back further, causing him to regress all the way back to a baby in diapers. Now an infant he immediately starts crawling around the rv in search of Jerky Jasper.
- When Uncle Grandpa turns himself back into a baby he's wearing nothing but his propeller hat and a diaper. In Uncle Grandpa Babies he wears a rainbow colored bib, yellow shirt, belly bag and has a smaller verison of his mustache. Also in Jerky Jasper his baby body is more realistic.
- Uncle Grandpa doesn't use his diaper at all during his time as a baby.
- This is the second time we see Uncle Grandpa as a baby. The first time was in Uncle Grandpa Babies.