Grilled Cheese Deluxe

Synopsis
Mordecai and Rigby are assigned to get a grilled cheese sandwich for Benson while playing a game to see who is the better liar. Mordecai and Rigby pretend to be astronauts, and they even fool a pair of real astronauts and their coworkers. However, they soon get themselves involved in a serious problem: trying to prevent a sample of antimatter at a space center laboratory from destroying the city (while pretending to be antimatter experts).

Plot
Mordecai and Rigby eat a grilled cheese deluxe while watching videos on the internet. After a series of videos, Benson barges in, asking for his grilled cheese sandwich. Rigby attempts to lie to Benson, but Benson didn't believe the story, and orders Mordecai to go get him another one.

The duo find themselves in a long line for the restaurant, Cheezers. They argue about who is the better liar. After Mordecai punches Rigby in the stomach from frustration, two astronauts in blue jackets goes around the line and enter the restaurant abruptly. Rigby recovers from the punch and teases Mordecai, touching his face and it pressured him into lying that they're astronauts too. They enter the place and got a grilled cheese, but then Rigby goes to the real astronauts and tells them that Mordecai is his instructor. Mordecai swiftly tells the astronauts that they have to go back to the compound.

One of them offers a ride while the other realizes that he never seen them before. Rigby explains that they got back from a ten year space trip and Mordecai includes that they got brought over. The astronauts decide to give them a ride and a tour of their compound. After entering the compound, Mordecai and Rigby say that they forgot their identification passes. The astronauts let them use their IDs and gives them a blue space jacket. Rigby puts the grilled cheese in his jacket and tells the astronauts that Mordecai wants his in pink. Mordecai then explains that he borrowed a pair from Dr. Askovich (who was standing in front of them). She says that she doesn't remember Mordecai who tries to remind her of the conference. She then looks uneasy and runs away.

A montage of Mordecai and Rigby getting a tour while making the astronauts laugh with their lies played, and the group make a last stop at the Anti-Matter Chamber. One of the astronauts greets the only scientist named Jimmy then jokes that he can't understand what these scientists say. Rigby tells another lie, saying that Mordecai knows about anti-matter. Mordecai tries to tell the astronauts that Rigby knows more which leads to an argument about who knows more while a alarm sound is going off. Jimmy explains that he's having trouble with the anti-matter and is interrupted when an astronaut tells Mordecai and Rigby to help. After messing around with the buttons, Major Williams comes and yells at them. The alarm becomes louder as the anti-matter becomes unstable. The astronauts put Mordecai and Rigby into the chamber so they can fix it.

They argue about whose fault it is, so Mordecai lies to the astronauts that he has a condition which makes him forget things in stress and that Rigby is an idiot. Jimmy explains that they have to throw a solid into the ant-matter. The astronauts tell Mordecai to throw Rigby into the anti-nucleus. Mordecai grabs Rigby (who's crying), but takes the grilled cheese and throws it into the anti-nucleus. The anti-matter explodes and becomes stable, causing Mordecai and Rigby to slam into the door. When everybody came to them, Rigby tells them that they're not astronauts. The astronauts throw them outside and threatened them. Mordecai and Rigby returned to Benson who questioned about what happened to his grilled cheese (which is burned up). Rigby tries to explain the truth, but Benson believes Mordecai who lied that they accidentally ran over it.