"Ed in a Halfshell" is the 21st episode of Season 2 and the 47th episode of Ed, Edd n Eddy. In this episode, Sarah has Ed take care of Jimmy while she is at her ballet lesson. Later after seeing how much bonding two people do together, Eddy takes Jimmy under his wing as a temporary apprentice and tries to make Jimmy a scammer like himself.
The Eds are busy setting up their new scam "Gerbil For A Day" (Ed being the gerbil). The scam is a failure, as there are no willing customers, and Sarah shows up. She makes the Eds play with Jimmy while she's at her ballet lesson so he will have someone to play with (also threatening Ed that she would break his model rocket in two if he didn't). She gives Jimmy a whistle in case The Eds cause him trouble, and she will come to his aid. The Eds decide to play games, much to the misery of weaklings Jimmy and Edd, so Eddy chooses dodgeball. After causing Ed pain, Eddy turns his attention to Edd, who flashbacks to the torment of gym class and a mysterious "dodgeball incident". This memory frightens Edd so hard that he (along with Jimmy) breaks down into anguished tears of fear. After that calamity, Jimmy decides it's his turn. Eddy says "No way!" to this since he claims it is still his turn. Jimmy is about to whistle for Sarah when Ed pleads Jimmy to not to since "Sarah's bad for Ed!". He then lands on Eddy while telling him not to hog the ball as well as saying to let Jimmy have a turn. Jimmy is happy that he gets a turn and to make it easier for Eddy to stay in position, Ed then rubs Eddy's shirt on his head a few times before sticking him to the garage door like a magnet. After Ed gives Jimmy the ball, Edd notes that the position is way too far for Jimmy and asks him to move Jimmy closer. Ed brings Jimmy closer and says to him it is his turn to hurt Eddy. Eddy mocks Jimmy that he will not hit him that hard, but this proves to be a mistake as Jimmy is incredibly angered by this, hitting Eddy so hard with the ball that Eddy falls through the garage door. Ed and Jimmy celebrate, with Ed acting like an older brother and Jimmy mimicking him.
Eddy (after Edd explains the reason Jimmy's copying Ed to him) decides to mold him into a master scammer. After a series of tests, which involve things like manipulation of Ed in to doing the heavy lifting and throwing eggs at a picture of Sarah (and Ed and Edd), it's time for Jimmy's first scam. Jimmy goes for a trampoline scam, which is more successful than any of Eddy's previous scams (and Edd even admits that he would never have thought of making a trampoline from the materials that Jimmy used, to which Jimmy replies smugly that it was obvious he wouldn't, making Edd angry). Eddy tries to take 50% of his profits, but Jimmy decides not to share with his teacher.
Eddy attacks him and they fight. Becoming danger-prone, Ed blows the whistle that Sarah gave Jimmy. Edd tries to warn him about it, but is too late. The boys keep going until Sarah arrives crashing. Jimmy tries to look as pathetic as possible, rubbing dirt in his own eyes. Sarah promptly shoves Eddy and Edd down Ed's throat and through his ears, then she and Jimmy leave for the candy store. Edd remarks that Eddy truly created a monster and Eddy replies that it makes him feel all warm inside. Ed tries to say something, but can't so Edd says to not talk with his mouth full.
Edd mentions his phobia of dodgeball, along with his gym class trauma when Eddy forces him to play. On the old Cartoon Network website, the biography of Edd mentions that he is excused from gym class, citing the dodgeball incident. However, he is seen in gym class in Ed, Edd n Eddy's Hanky Panky Hullabaloo and "Cool Hand Ed."
Ed stuck Eddy to the garage door with static electricity, yet Ed is unfamiliar with static electricity until Season 5's "Every Which Way But Ed." As Ed isn't very brainy, he may have forgotten about how static electricity works between this and the later episode.
Eddy gives a wedgie to Jimmy with one egg, but two yolks are seen.
Eggs do occasionally contain two yolks, so this may or may not have been intentional.
When Jimmy reattempts throwing eggs at Sarah's picture, Eddy gives him three eggs. When Jimmy throws them at Ed and Edd, more than three eggs are seen.