"The Grumpy Gremlin" is a Season 3 episode from the Smurfs cartoon show.
Peewit goes out into the woods to chop firewood for the king, happily singing while the forest creatures endure having to hear him sing anything. He soon finds a suitable tree for chopping, but as he gets close to it, he smells something strange about the tree, saying that the tree must be so rotten that it stinks. Nevertheless, Peewit gives it a few good whacks, which causes the tree to fall, though it also causes someone to come out of the tree and complain about the mess he caused. He calls himself Gaston the gremlin, saying that the tree is (or rather, used to be) his home, and that not only did Peewit destroy his home, but he also caused Gaston to spill his grelch...a foul-smelling concoction made of wild onions and garlic relish that the gremlin was cooking. Peewit tells Gaston that he's sorry for wrecking his home, but that he could easily find himself another one. But Gaston isn't willing to let Peewit go about his way without having him promise to find the gremlin a new home. Peewit shows that he isn't interested in helping the gremlin as he packs up the firewood in his wagon and rides off. Gaston yells after Peewit, saying that he won't be able to get rid of him that easily.
Meanwhile, Papa Smurf is watching his little Smurfs gather up a harvest of smurfberries out in the forest, saying that because of the bountiful harvest they will have a celebration at the Great Oak on the following day. As Hefty carries two heavy baskets full of smurfberries on a pole, Greedy decides to help "lighten the load" by eating some of them straight from the basket.
On the road to the king's castle, Peewit feels ready to dine on whatever being's served for dinner when he suddenly smells the odor of grelch in his wagon. It is Gaston, who teleports himself into the wagon and tells the home wrecker that he isn't leaving until Peewit finds him a new home. Upon his arrival inside the castle grounds, Peewit brings Sir Johan to show him the gremlin that he brought back along with the firewood, only to find that he disappeared without a trace. Johan thinks that Peewit must have been imagining things and tells his friend that he needs a rest...as well as a bath when he smells the leftover odor of the grelch.
At the dinner table, the king's cook presents his liege with a meal of liver and wild onions, which he anticipates eating eagerly until he lifts the lid of the serving tray and sees that the liver has no wild onions with it. The cook tells the king that he doesn't know where the onions for the liver are, that he had a sackful of onions up until that evening. Peewit suspects that it's the gremlin who took the onions and goes into the kitchen to find Gaston with one of the ingredients for his grelch. Peewit tries to pounce on Gaston to stop him, but Gaston teleports himself away, and Peewit is left sliding down the kitchen counter right onto the serving cart. Gaston again harasses Peewit with the question of whether he has found him a new home, but Peewit is more interested in capturing the gremlin by placing the lid over the serving tray to trap him. Unfortunately, as Peewit arrives in the dining hall with the serving tray to show the king and Johan the truth about the gremlin, he lifts the lid and reveals nothing underneath it but a lingering awful smell. Peewit says the smell proves that the gremlin was there, but all Johan can say is that the smell proves that his friend needs a bath and so carries him away from the dining hall.
Alone in his bed at night, Peewit thinks that he's going to forget all about the gremlin who's been bothering him when he falls asleep, but he barely catches a few winks when he starts hearing banging noises. He looks around and sees that Gaston is under his bed fixing a shoe with his hammer. Peewit is so upset with the gremlin that he tells Gaston to stop cobbling shoes, but Gaston tells Peewit that cobbling is what gremlins do, and if Peewit finds him a new home in an oak he will be gone. The hammering noise awakens Johan and the king, who get out of bed and head in the direction of where the noise was coming from. It turns out to be Peewit's bedchamber, where the young jester claims he has caught the gremlin responsible and trapped him inside his blanket. But as Peewit unravels the blanket, all that is wrapped in the blanket was a hammer that falls onto the king's foot, hurting him. The king gets so angry that he commands Peewit to stop eating onions, to stop making noises, and to go to sleep or else. After Johan and the king leave the bedchamber, Gaston reappears to take back his hammer and to continue his cobbling, leaving Peewit with only one solution: he will help find the gremlin a new home in the forest the first thing in the morning.
The following day, as Peewit takes Gaston into the forest to look at oak trees to find the right one that he can call home, Gaston rejects all those that he has seen except for one that Peewit recognizes as the Great Oak. He says that the tree belongs to the Smurfs, but Gaston sees it as the perfect home and claims it for himself. Not wishing to have the gremlin hang around him any longer, Peewit leaves Gaston to his new home and has Biquette gallop as fast as he could so he could get to the Smurfs and tell them about the Great Oak's new resident.
Sometime later the Smurfs have gathered around the Great Oak to decorate it with flowers for the celebration of the smurfberry harvest -- something that Hefty likes doing, but what Grouchy hates (the decorating, not the Great Oak). But then the Smurfs start smelling something awful that's coming from the Great Oak, and Hefty starts hearing what he thinks is a woodpecker inside the tree. Gaston pops his head out of the tree to see who's near his new home, and warns them to stay away and not do anything to his home. The Smurfs refuse to let Gaston take over their tree and come closer so that Hefty could have a few words with him, but Gaston flings some of his grelch toward them, causing the Smurfs to run and find Papa Smurf so that he can deal with the gremlin inside their tree.
Peewit and the Smurfs found Papa Smurf at the same time to warn him about the gremlin, and so Papa Smurf goes with them to the Great Oak to talk to Gaston about the possibility of him sharing the Great Oak with the Smurfs. But Gaston isn't interested in sharing his new home with anybody, saying that the two things he hates is sharing and company. He tells Peewit that he will have to stay with him until he finds another home for the gremlin, but Peewit says that he can't stay with him and that there are no other great oaks in the forest. Papa Smurf does say that there is one on the other side of the forest past the Purple Falls, but before Papa Smurf could warn him about the place, Gaston transports himself there and sees that the place is perfect. However, Gaston isn't aware that a fire-breathing dragon lives in that area, which is what Papa Smurf wanted to him about...and which Peewit brings his friends over to find Gaston before he and his grelch gets roasted.
Upon reaching the Purple Falls, all Peewit and the Smurfs could find is the pot that Gaston used to cook his grelch in, fearing that they were too late. And soon enough, the dragon finds them and chases Peewit around with his fiery breath while the Smurfs hide for safety inside the pot. But as Peewit climbs up an oak tree to avoid being burned to a crisp, Gaston pops out of the tree's hole to tell the dragon to beat it and stop trying to burn down his house. Peewit and the Smurfs see that the dragon actually listened to Gaston, who reveals to them that the dragon actually likes grelch and has been eating out of his hands. Gaston wants to thank Peewit and the Smurfs for helping him find a new home by having them stay for dinner, but Peewit and the Smurfs decline, not wishing to partake in any grelch. As they leave Gaston with his new pet, they happily feast together on the pots of grelch the gremlin has made.