Corey and Barney usually help each other out with things. However, when Corey helps Barney with things, he usually doesn't give him exactly what he needs and usually makes things worse than they were before. Corey relies on Barney to help his band succeed at the things that they often times try to do. Barney will also constantly be hosting a huge event and hire Corey's band to play there. Most of the time, Corey has to meet some certain requirements before he can play there. Corey will put major effort into accomplishing this, but when he does, he will usually just be lying about it. Neither Corey or the rest of the band show any shame or guilt whatsoever for lying to Barney.
Barney hired Grojband to play at his daughter's wedding but Corey only wanted to play at his wedding because there was cake there. However, when he heard that none of the members of Grojband have actually been in love, he had to turn them down. Corey promised Barney that he was already in love with Laney. Barney didn't believe him so he told them to prove it. Corey and Laney went on many fake dates together to fool Barney. After the fake dates, Corey and Laney told Barney about everything they did. Laney told him about all of the romantic things they did which did not amuse him. Corey then told him about how much horrible things happened to them and what terrible things they did to their friends when dating, emotionally touching Barney, and making him tear up as he literally puked from love and allowed them to preform on stage. Instead of dedicating the song to Bake Barnera and her husband like they had promised Barney, and instead dedicated it to Kin and Kon because of how they betrayed them earlier. Everyone still liked their song and they still got their cake reward anyway.
Barney hired Corey and the band to play at the grand opening of the Salad Barn. Corey lied to Barney, saying that he was a vegan band, but Trina eventually revealed to Barney that they were lying. Barney was disappointed in them for lying and he told them that it hey still had a chance at playing at the grand opening if they became legitimate vegans. Corey and the band tried to become real vegans at first, but later decided that it would be a bad idea to do that, so they lied to him again and he believed them. They played their song, which Barney enjoyed and after their performance, Corey admitted that they weren't really vegans. Barney was shocked to hear this and Corey explained it through a moral. In response to this, Barney just walked away saying "Uh, hee Hee, sure kid."
Barney hired Corey and the band to play music at the Gym Barn to help play some motivational music for the people there. He first introduced them to the threehardest toplease members of the gym and told them to rock them into shape. Corey and the band ate Jack attack energy bars which made them compress five weeks worth of music into three seconds which was a complete overdose of music. This made the three old ladies turn into giant Gorillandmas who destroyed the Gym Barn and ran psychopathically around Peaceville, leaving Barney in complete and utter shock. Corey didn't care about his shock as he happily admired how good he did at making them get strong. Corey happily nudged Barney and Barney screamed in terror and fainted in the floor. Corey eventually returned them all back to their normals states again. Kon asked him if they helped Barney by doing this. Corey carelessly said "Doubt it" and signed off the episode.
Corey, along with the rest of Peaceville were all really bored and depressed when Candy Barney's Candy Barn burned down. Later in the episode, while under the control of Torbo's bracelet, Corey said that the party they were having was way better than his Candy Barn.
Barney informed Corey all about the mimes who are trying to steal his spot in the park and warned them all about the things that they do. Barney then fell under the control of the mimes and offered Corey an invisible sausage. Corey was really happy to see it and he tried to take it until he realized, he was infected. When Corey found out what had happened to him, he freaked out. While under the control of the mimes, Barney was against Corey, trying to get him out of the performance area. Corey played the song Quiet Noise, which freed Barney from his mime trance.
Coffee Barney allows Grojband to plat at the Bean Barn for the Hipsters. He congratulates Corey on succeeding in making the hipsters the most attentive he had ever seen them. Later when Grojband's are about perform, he asks everyone to welcome Grojband, and is impressed how they seem to show more attention than he had ever seen them.
Corey booked a gig at Movie in your car Barney's Movie in Your Car Barn. Barney thanked them for playing at his event and offered Corey some popcorn. Corey took some. He also offered them another gig at his next event but Corey turned it down. After he did, he either accidentally or intentionally knocked him over and made him drop to the ground and ignored him so that he could tell everyone his moral.
Corey wanted to buy a cowboy hat from Barney, but Barney denies his request, telling him that he can only sell it to people who are truly country. So as usual, Corey and the band devise a way to trick Barney into believing that they were country, which Corey decides the best way is to create a country of his own. During I Must Be Losing My Mind, Corey quotes Barney and described him as "A wise man" which flustered him, and made him blush. Afterwards, Barney finally concedes that Corey losing his own country truly proves that he's country, and finally gives Corey his cowboy hat.
While the entire town descends into chaos due to the fear of the apocalypse, with Barney and Mayor Mellow preparing to charge at each other. Corey and Grojband sing If The World Is Ending to try and calm everyone down. Barney and the mayor both pause to listen, before Corey reaches out and makes the two shake hands, bringing peace to the two men.
In order to save the world from the apocalypse, Barney helped Grojband get into outer space. He gave Corey and the rest of the band a bunch of astronaut suits and taught them all about going into space. However, he also allowed Trina to come into outer space with him and, ignoring Corey's concern, he told them that he's making them go to space together like that because they're family and it would make everything all the more fun.