Corey and the mayor have a very complex friend-enemy relationship. It has comprised of the Mayor getting annoyed at Grojband's antics, as well as hindering their efforts for a gig. While Corey and Grojband come up with various schemes to outfox the mayor and attain the gig. Recently the two have put their differences aside and are on mostly neutral terms.
After hearing about Corey's chicken pox party, Mayor Mellow quarantined the entire party inside of a bubble. Corey was not happy with Mayor Mellow for doing this, but he tried to make the best of it. Surely enough, he did. After the party ended, Mayor Mellow appeared out of the bushes and asked Corey what he would do for the next eight days of being trapped in the bubble? Corey made a very terriffied face when he did this. Corey however, didn't seem offended by this as he signed off the episode, saying "the only cure for party fever is a wet blanket."
After Trina successfully manages to exploit Kon failing math for six years so that Grojband can not play at the Trimathalon, Corey decides to plea to Mayor Mellow to have Kon participate, so that if he wins, not only would he'd pass six years of math in one day, but let Grojband play there, but before Corey can get a word in, Mayor Mellow consents to that idea.
Mayor Mellow mistook Grojband for bears because they were all wearing costumes so he locked them up in the zoo. Corey tried convincing him that he wasn't a bear but Mayor Mellow ingored this, and treated them like the animals in the zoo, to which he threatened him and the rest of Grojband that they'll end up on Mother's disappointment wall if they didn't perform. After a while, Grojband played a song and all of the animals broke out of the zoo which resulted in Mayor Mellow getting attacked.
The mayor introduces Grojband at the Bubble Fest, and to start off the festival he tries to open a giant bottle, but when he has trouble doing so Corey offers his own bottle of pop. Unbeknownst to him, Trina had shaken this bottle up, so when the Mayor opened it, the cap blew off with explosive force and got lodged in his brain. This injury caused him to hate bubbles and places a ban on them.
Corey and his band preformed for Mayor Mellow to get into the Lady Rage Music Festival. Mayor Mellow clapped his hands and told him that he'd be perfect. Corey became overexcited smiled widely while his eyes twinkled with stars in them, but his spirits were soon shattered once Mayor Mellow told him that he wasn't talking about him, he was talking about Laney.
After Mayor Mellow receives a tip off from Trina of Corey's lounge party, he approaches abd demands entry. Although the guard doesn't let him pass, Corey lets the mayor in himself. Mayor Mellow then reveals himself to be Melodious Monk, a champion lounger, and permits the lounge as well as declaring a holiday for lounging. All seems well when the whole town takes to lounging, however this attracts the attention of Captain Tighty Whitey and his crew who decide to take the opportunity to plunder the town while everyone is off their guard. The pirates attempt to search for gold and treasure, and attempt to get all of the citizens to dig for them. So Grojband devises a way to try and get them to find some gold so they'll leave. The only available gold they can find is Mayor Mellow's gold medallions, and with some reluctance he finally gives them up. Afterwards, Corey and Mellow join together to sing Nothing and educate them that there are more important things in life than gold.Grojland", shortly before declaring war on them. He then goes so far as to isolate Grojland from the town with a wall and prohibits entry into the country. The mayor goes to drastic measures in his war against Grojland, including setting up a tank outside the wall. When Corey throws a volleyball over in a bid to play with Peaceville, Mayor Mellow fires a projectile back and mocks their pathetic attempts at combat. The mayor also forbids anyone from entering and leaving the country to further entice their surrender. Eventually Corey negotiates with Mellow and he agrees to return Trina (who had escaped) as she one of their citizens. After Grojband sings the Grojland National Anthem, Corey tells him knock down the walls and he welcomes them back to Peaceville.