NanoZIM

"There is an alien in my guts and he's trying to destroy my brain!"

- Dib

Plot Summary
When GIR forgets to close Zim's front door one night,Dib sneaks inside Zim's base, takes a picture of him without his disguise on and escapes before the alien could catch him. Once at home, Dib inserts the picture on a floppy disk and places it inside an envelope, intending to send it to "Mysterious Mysteries of Strange Mystery", in order to prove that aliens exist. Little does he know that Zim formulated a plan to shrink himself down to microscopic size to invade Dib's body via a microscopic nanoship. Once inside, he accesses Dib's nervous system, giving him control of Dib's arms and, as a result, making him crush the floppy disk. When Dib tells him that he has a copy of the disk hidden in his house, Zim attempts to travel to Dib's brain and perform a brain wipe, to stop him remembering where he hid the disk copy.

Fortunately for Dib, his father has been working on some technology that may just help Dib stop Zim before it's too late: another microscopic submarine, with videogame-like control. However, Dib has to be careful, because he's extremely vulnerable due to Zim being inside him. When Gaz mistakes Dib's efforts to defend himself from Zim for a video game, she gets excited and asks Dib to let her play. Unfortunately, Zim manages to attack Dib's brain, making Dib forget where the disk is hidden.

Zim also attacks Dib's nerves, making him twitch, speak, and move erratically, so Gaz takes his place and begins to play what she thinks is a video game. Being a highly experienced gamer, she defeats Zim very quickly, inserts her name in a High Score screen and walks away. To add insult to injury, Dib ends the battle by literally flushing Zim from his system.