Belly Brothers (also known in the title card as Belly Bros) is the first episode of the show Uncle Grandpa, and the first overall episode of the series.
When a kid named Belly experiences difficulties with putting on his shirt due to his big belly getting in the way, Uncle Grandpa tries to show him how cool a big belly can be.
- Pizza Steve
- Mr. Gus
- Giant Realistic Flying Tiger
- Belly's Mom
- Taco Wolf
- Beary Nice (Cameo)
- Hot Dog Person (Cameo)
- Crazy Baby (Cameo)
- Uncle Grandpa's Sheep
- Tiny Miracle (Cameo)
- Adam (Cameo)
- Eric (Cameo)
The episode begins with Uncle Grandpa sleeping in his bed dreaming about chasing a sheep. When he finally catches the sheep, the sheep turns around and bites his nose. This, in turn, causes Uncle Grandpa to wake up. He gets up and says "Good Morning" and approaches the sheep. He takes off his nose and feeds it to the sheep before going to his drawer full of noses and putting on a new one. He takes off and immediately goes to Giant Realistic Flying Tiger's room to greet her with a warm "Good Morning". At first, Tiger is ticked off and throws a pillow at him. Rather than get angry, Uncle Grandpa tells her that he loves her, and this causes Tiger to give him cute kitty eyes and meow. Uncle Grandpa then travels up a pole to enter Mr. Gus's room, where he greets Mr. Gus with a "Good Morning". Mr. Gus greets him back as he works out. Uncle Grandpa asks if Mr. Gus could launch him through a canon. Mr. Gus agrees and shoots him through the canon. Uncle Grandpa goes sailing through the RV. He ends up in the kitchen where he is caught by Belly Bag. Uncle Grandpa greets him with a "Good Morning" and Belly Bag happily greets him back. Uncle Grandpa then looks up at the ceiling where Pizza Steve is squished up. Uncle Grandpa greets him with a "Good Morning". Pizza Steve slowly drips himself down from the ceiling before bouncing up and greeting Uncle Grandpa. Pizza Steve asks Uncle Grandpa what he has in store for them. Uncle Grandpa replies by asking the Uncle Grandpa who is driving the RV. Then Uncle Grandpa driving the RV points to another Uncle Grandpa with a bunch of noses and tells Uncle Grandpa to ask him. Uncle Grandpa asks, and the Uncle Grandpa with a bunch of noses replies with a loud sneeze that sends all of his noses flying around the cockpit of the RV. This causes the RV to swerve out of control.
Meanwhile, Belly is trying to get ready for school. Belly's Mom reminds him that he will be late if he doesn't leave now. Belly tells her to wait as he desperately tries to get his shirt on. The shirt will not fit over his big belly. Suddenly, the RV crashes through his room and Uncle Grandpa pops out of the window and into the middle of his room. Uncle Grandpa greets Belly with a "Good Morning". Belly asks who he is, and Uncle Grandpa tells him. Belly Bag goes on to explain exactly who Uncle Grandpa is to Belly. Uncle Grandpa asks Belly what's going on, and Belly explains to him how he can't get his shirt over his big belly. He also explains how he hates his big belly and proceeds to smack it a few times. Uncle Grandpa sympathizes for him and recalls a small anecdote in his younger years where he was upset about having a big belly, but then he found out that big bellies are actually an awesome thing to have and that took away his emotional pain. After explaining his story, he gives Belly an example of why and how big bellies are awesome by dribbling his belly like a basketball and using his belly like silly putty to get a mold of his face. Belly Bag also explains that the best part of having a big belly means that Uncle Grandpa gets to wear him. Uncle Grandpa then explains the belly brotherhood to Belly.
Belly is still not too convinced, and asks if he can just make his shirt fit over his body. Uncle Grandpa calls in Mr. Gus to bring the shirt down over the kid's stomach. Mr. Gus comes in and attempts to do so, but accidentally rips the shirt instead. Belly panics, so Mr. Gus eats the torn shirt, tries to pretend nothing ever happened, and leaves. Uncle Grandpa reassures Belly that he will get a new shirt for him. Uncle Grandpa reaches into Belly Bag and digs through a few drawers before retrieving a plain t-shirt. He pulls it out and asks about Belly's interests. Belly tells him that he likes night wolves, so Uncle Grandpa airbrushes night wolves onto his shirt. He puts it on Belly, but Belly disappears. Uncle Grandpa realizes that he accidentally sent Belly into another dimension. Uncle Grandpa transports himself and Belly Bag into the same dimension they sent Belly to in an effort to save him.
Uncle Grandpa lands in the realm of the night wolves and immediately sees Belly being attacked by the Taco Wolf. Uncle Grandpa advises Belly to use his belly to defeat the Taco Wolf, but Belly confesses he doesn't know how. Uncle Grandpa shows him an example by using his own belly as a fist to punch the Taco Wolf several times. He then turns his stomach into a hammer and smashes the Taco Wolf into a bunch of tiny little tacos. Uncle Grandpa explains the belly brotherhood rule of never leaving a belly brother behind to Belly before suggesting they leave. When they try to leave, however, they find that a bunch of Night Wolves have them surrounded. The Night Wolves corner them before kidnapping them and bringing them back to the wolf den. Once in the wolf den, the Night Wolves throw Uncle Grandpa into a pot of soup. The Night Wolves drop Belly so they can go feast on Uncle Grandpa. Uncle Grandpa tells Belly to use his belly to save them. Belly insists he has no idea how to use his belly. Uncle Grandpa reassures him that he believes in Belly as a belly brother. This is enough for Belly to finally take action.
An epic fight scene begins where Belly uses his belly to body slam te Night Wolves away from Uncle Grandpa. Belly saves Uncle Grandpa from the pot of soup and they immediately set out to defeat the Night Wolves with their bellies. After defeating the Night Wolves with their bellies, Belly tells Uncle Grandpa that he has learned to appreciate his big belly. Uncle Grandpa calls upon Giant Realistic Flying Tiger to get them out of the Night Wolf dimension and back into their own dimension. They get back into Belly's room and Belly says he does not need a shirt because it would only cover his awesome belly. Uncle Grandpa seemed happy with that answer. Belly's mom comes in to check on Belly, and complains when she sees he does not have a shirt on. Belly reassures her that he does not need a shirt thanks to Uncle Grandpa. His mother seems confused so Belly goes to introduce Uncle Grandpa to his mother but Uncle Grandpa is already gone. Uncle Grandpa is then shown driving his RV surrounded by a bunch of tacos.
- Tiny Miracle makes a cameo appearance.
- Beary Nice and a hot dog that might resemble Hot Dog Person were seen around the world. There was also a baby head that was similar to Crazy Baby's, a head of a kid that looked similar to Adam and a head of a dark skinned kid who might be Eric.