For Christmas Jack has received a chemistry set and he decides that he is going to create the perfect insecticide in order to get rid of the roaches once and for all. But instead of getting rid of them, they start multiplying infinitely!
Official Synopsis, 
Cloning Around is the 67th episode of Season 1, and was remade as the seventh episode for Season 6 under the title The Great Invasion. Jack accidentally invents a gas that clones whoever it's used on.
Episode starts: During Christmas, Oggy and Jack are opening up their presents. Jack receives a new science kit, to his excitement while Oggy receives a new canister of insecticide and another box of chocolates from the events of Bitter Chocolate. Dee Dee, however, steals the box, prompting a chase, ending with Joey slamming a pillow on Oggy and Jack after a slip on one of the chocolates on the floor. The Cockroaches manage to win, causing Jack to try out the new insecticide. Unfortunately the insecticide proves to be a dud, as the roaches were shown dancing around the insecticide like smokescreen.
Jack, having enough of the Cockroaches, decides to experiment with his new science equipment to make a more useful, deadly version of the insecticide. Oggy hears his cousin laughing evilly as Jack slams the door open on Oggy. The door closed and Oggy falls down. Oggy gets up afterwards. At the kitchen, Jack uses Joey, who is eating a pickle, as the guinea pig for his new spray. To his horror, Joey sprouts a large tumor from his back which eventually separates and creates an identical copy of himself. Jack tries again, but it creates two more Joeys from the biceps. The multiple Joeys, along with Marky and Dee Dee begin to chase him in complete horror, as Oggy watches in confusion.
Then, as the cloned cockroaches beat up Jack, Oggy uses the spray on them again, unaware of the effects, but Jack warns his cousin to not spray on them. He did anyway. This causes another copy of cockroaches to sprout as Oggy understands the situation: Dee Dee on the lower lip, Marky on the head, and four Joey's on the back, body, foot, and eyeball. Oggy runs away in terror, dropping the spray on which one of the Joeys take, and following that, Jack, useless to do anything with the cloned cockroaches, follows behind in shock.
In the kitchen, the multiple cloned roaches abuse the spray to steal food on the fridge. They reach the top unveiling pig snouts in a can by three more Joeys. The cousins formulate a new plan. The Cockroaches happily indulge themselves with the contents of the fridge until they notice Oggy and Jack, wearing raincoats, properly prepared to stop the army of clones. This results in a massive curb-stomp battle of fishing like in Fishing Frolic, ending in the cats' favor. One last Joey that needs to be caught, still has the cloning spray and rapidly fires it at the captured cockroaches in the bag, much to the cats' shock.
This results in the house being flooded with the cloned roaches. As they evilly laugh away, they once again notice something: the cloning spray has affected the cousins as well, creating an even larger army of Oggy's and Jack's. The episode ends as the cloned cats begin to beat up the Cockroaches, now finally having the upper hand.
- In the remastered episode, when Joey laughs at Jack, the angle seems to be different.
- Oggy and the Cockroaches - The Great Invasion (S06E07) Full Episode in HD (published by OGGY on Jan 1, 2018, on YouTube. Accessed Sep 7, 2019.)