Let's Party, Guys! is the 6th episode of Season 4. It's Joey's birthday, and Marky and Dee Dee decide to make a big party for him, only to cause a HUGE problem at the house, which angers Oggy and Jack.
Dee Dee and Joey look at their old chest. The chest is be found of the roaches' old toys and Joey's birth certificate and Dee Dee surprisingly saw Joey's birthdate. Dee Dee check his phone. It's on 14 and 15 June and it's called tomorrow. Marky and Dee Dee anxiously think they forgot their brother's birthday. So they must hide their anxiety from Joey. Two of them saw Oggy's blog account and plans the birthday party and hacks Oggy's account.
The trio has been waking up. Dee Dee and Marky are laughing that they still forgot Joey's birthdate. So Joey beats the duo but someone brings an invitation card themed Joey's birthday. Joey affected and thanked his brothers. Another flock of roaches also brings the card. But the havoc makes a serious problem for Oggy who runs away from his house because millions of roaches from the entire world has come to the party. Because too many roaches, Joey roars and attempts to tell the roaches to get out but Joey and his brothers are beaten and chased by other roaches. Oggy has put up his tent and ask help to Jack that has arrived. So, Joey, Oggy and Jack are working together to prevent the roaches from making another havoc and drive away from them. After the roaches are leaving because of the toxins and poisons spray, Oggy, Jack and the roaches brothers celebrate, get poisoned and flee from the house where is put out of boundaries until the toxins and poisons are totally cleared. So, the five of them celebrates Joey's birthday except the gift is a flyswatter. The view zooms outside the tent while Oggy and Jack beat the cockroaches as the episode ends.