The episode starts with various T.U.F.F. agents, among them Dudley, Keswick, and the Chief, breaking into Kitty's apartment to throw a surprise birthday party. But instead of cheer, they get blasted by a startled Kitty, who also injures the clown they hired. Later that day, Dudley is still determined to throw Kitty, the "GREATEST BIRTHDAY EVERRRRRRRR!", but Kitty tells him not to bother, as all of her birthdays have been a disaster since she was a kitten. With Keswick's Flash Backer, we see that a five-year-old Kitty accidentally destroyed her bounce house and injured her friends (also leaving them in their underwear), and at age twelve, ate the magician her mother hired (he was a mouse, so naturally she'd eat him). After the flashbacks, Snaptrap appears on screen and announces that he has a plan so diabolical that... it couldn't be described by words. He also makes an idiot of himself by asking if the red light is on, and then blasts Larry, then the camera. Kitty immediately jumps at the chance to catch Snaptrap, saying that it's what she wants for her birthday. Back at D.O.O.M., Snaptrap reveals that he never had an evil plan, he just wanted to be on TV, and then throws Larry into the shark tank for talking back to him. It then turns into lunchtime, and Snaptrap forces Ollie to trade with him or perish because his mom packed him pimento loaf. But after eating Ollie's sandwich, Snaptrap finds out too late that it was grilled cheese on cheese bread, and has his usual allergic reaction to it. After his henchmen laugh at him, Snaptrap then comes up with his plan: Rid the world of cheese!... which he will do after he takes an antihistamine and get a straw for his juice box.
Dudley and Kitty manage to catch Snaptrap at the magnet store, where he and his goons are stealing refrigerator magnets, but Dudley ruins this by tying balloons to Kitty's tail, and sending them in midair. Crash landing back to Earth, the duo then attempts to stop D.O.O.M. when they steal a giant chili pot, but Dudley gives them away with the noisy birthday card he got for Kitty, causing them to be caught by Snaptrap. Once at D.O.O.M. headquarters, Dudley and Kitty are tied up and Snaptrap rides up to them on a lift and reveals his plan to melt all the magnets down and build a giant cheese magnet to rid the world of cheese, and cows, just to make sure that they never make cheese again. But before Dudley and Kitty are lowered into the lava tank, Dudley comes up with an escape plan: Dudley tells Snaptrap it's Kitty's birthday, and Snaptrap reveals that he never kills his enemies before they celebrate their birthday. With D.O.O.M. distracted setting up for the party, Dudley uses Keswick's flashbaker to create a birthday cake that Snaptrap pretty much gobbles down... A cheesecake Snaptrap is fattened up again, his inflated body hitting the controls on his lift, which activated all the bases weapons, which take down the henchmen, and free Dudley and Kitty, who commence to beating up the D.O.O.M. agents. Dudley then fires Snaptrap (with a pie) into the ray of his cheese magnet, where all the cheese flies down, he screams, causing it all to fall into his open mouth and make him grow fatter. After D.O.O.M. is defeated, Dudley and Kitty go forth to continue Kitty's birthday and end up running from falling cows, thanks to Dudley, who accidentally set Snaptrap's magnet to "Cow".