The episode begins with Goat & Jamie talking about Racheal. Goat tells Jamie that he should keep trying to ask Racheal out. Jamie says that the last 50 times has always ended with no and the last time he tried, he got punched in the eye. Goat tells Jamie to not give up and eventually he will succeed. He then receives a call from Alex, the very same Alex from "MTV Downtown". It is revealed that he and Jen are engaged and are going to get married tomorrow and that Goat has to be there as he is the best man. It is also revealed that during a concert Goat went to, he spoke with Alex on the phone, without realizing what the conversation was about. Goat assures Alex that he will be there. Coop comes over and asks if there is anything to eat. The only food that is left is Pizza that has been left out for months. Goat shows that it is safe to eat by having some. Coop decides to go to the Speedy Mart to get food. When he comes back, it shows Goat on the ground.
At the hospital, Goat's stomach needed to be pumped in order to get rid of the toxins and bacteria that was infesting Goat from the bad pizza. While most of it is gone, there are still a few strands left, that are giving Goat a stomach ache. Kiva says that they should let Goat rest and that his body should take care of the rest of the bacteria. However, Goat states that he needs to get to New York in order to get to Alex & Jen's wedding. Coop comes up with the idea of using Megas, which Kiva adamantly refuses to. Kiva says that Coop would be a bigger danger to Goat than any virus or illness. Kiva also says that the only way to even attempt this would be to have Megas shrink down and enter Goat's body. It is revealed that Coop installed a shrinking function in Megas. Kiva eventually relents, but warns Coop that whatever happens to Goat is on him.
Megas shrinks down and gets sterilized by the doctors. Megas then enters a pill, which Goat takes. Megas breaks out and begins exploring the stomach area. Coop reveals that the shrink ability runs on a timer and that they have only 30 minutes to destroy the bacteria and escape. Kiva warns that if they don't escape in time, they will grow back to normal size, while inside Goat. Coop comes across what he thinks to be the bacteria. He fights and destroys it. It is revealed to be a white blood cell. Megas is now perceived as a threat to Goat's body. Megas battles an army of white blood cells. It then escapes through the bloodstream. In addition of being attacked by white blood cells, it gets attacked by enzymes.
At one point, Megas accidently crashes into Goat's heart, giving him a heart attack. Megas uses an electromagnetic pulse to calm Goat's heart down. Megas makes its way towards Goat's brain, then goes back towards the stomach, while fighting white blood cells and enzymes.
After more fighting and another heart attack, Megas makes its way back to the stomach. After fighting even more white blood cells, it eventually comes across the stomach bacteria. Megas fights against the bacteria, but it was one of many. More bacteria battle against Megas. Megas eventually manages to destroy all of the bacteria, but would not have enough time to escape from Goat's mouth or nose. Coop realizes there is another way out and heads for the rectum. This causes Goat to "Fart" out Megas.
Goat has made a full recovery and is able to attend the wedding. Before they leave, one of the doctors informs Jamie that he is due for a prostate check. At the end credits, it shows Alex & Jen get married, while Coop & Jamie attend.
