NanoZIM
S01E05 - Airdate: 2001-04-13
Runtime: 30 min
When Dib finally manages to get a picture of Zim without him in his disguise, Zim formulates a plan to shrink himself down into a microscopic size to get into Dib's body and perform a brain wipe to prevent him from remembering where he located the picture. Fortunately for Dib, his father has been working on some technology that may just help Dib stop Zim before it's too late, though he'll been to be careful because he's extremely vulnerable due to the fact that Zim is inside of him.
Episode details and rating from TVmaze.