"Key to My Ed" is the 14th episode of Season 2 and the 40th episode of Ed, Edd n Eddy. In this episode, the Eds find a key and try to find out what the key unlocks.
Edd is holed up in his garage with the lights off when Ed and Eddy burst in and turn on the lights. Edd quickly yells at them to shut it off, as he's working on an experimental soda pop. Hearing this, his friends are quick to leap on him, and Ed drains the bottle of its contents. Seeing this, Edd yells at him to freeze, as any movement might set off the soda; Eddy, who is smarting from not having gotten a taste of the soda, proceeds to tickle Ed, making him shake wildly. Soon enough, the soda is set off in Ed's stomach, and Ed explodes out of the garage, spewing soda fizz everywhere as he flies through the cul-de-sac. When he finally comes down, it's in a crash landing in someone's backyard. His friends find him, but Eddy is soon distracted by another find: a key. Eddy believes that the key could open anything, from Al Capone's wallet to King Tut's tomb to some exploited cartoon character's theme park. Edd tries to convince his friend that they should just give the key back, but Eddy ignores him, as he thinks that the key is sure to open a door to some great treasure.
Eddy then leads his friends around the cul-de-sac in an attempt to find out what the key will open. After trying Jimmy's retainer and finding that the key doesn't work on it, Ed attempts to use the key on Beatrice's udder. Edd, still feeling guilty, tries to convince Eddy that they just have to give it back, even as Eddy uses the key on a manhole cover and Ed tries it on a fire hydrant. When Eddy gets fed up and yells at Edd, Edd says that they have to give it back. Hearing this, Eddy apologizes, but as soon as Edd turns his back, Edd receives a sharp kick in the butt.
Rolf then walks past, rolling a suitcase behind him. Eddy gets the idea that the key will open the case, and runs after Rolf, who has stopped next to Edd. Edd is moralizing on the state of humanity, but Rolf, not really understanding what Edd is rambling about, simply suggests that Edd should eat more fiber. He then notices Eddy, who is attempting the key in the suitcase's lock with no success. Rolf offers to show them what's inside; when Eddy accepts, Rolf opens the suitcase and pulls out an accordion, which he proceeds to play. Eddy angrily says that he's getting out of there, but Ed grabs him and starts polkaing. When the song ends, however, Eddy has managed to get his friends out of there, leaving Rolf strangely alone.
Fed up, Eddy heads to the lane with his friends to try and figure out a new approach. Another one of Edd's laments about how they must return the key to its rightful owner sparks an idea in Eddy's head, though, and shortly thereafter every kid in the cul-de-sac save Jonny receives an anonymous message informing them that "We have what you lost. If you ever want to see it again, come to the lane at 3:00 and bring a bag of jawbreakers."
At the given time, the Eds head for the lane, Edd complaining that he wasn't talking about holding the key for ransom. Along the way, they trip over Jonny and Plank, who are napping; when Eddy and Edd head onwards, Ed carries the boy and his board away to protect him from the vultures. In the lane is Kevin, and Eddy surmises that he holds the key to Kevin's bike chain. Rolf then arrives in the lane, and accuses Kevin of having breached his trust. Kevin makes a similar accusation, and the two fight, with Kevin wanting his headphones back and Rolf wanting his eggplant cup. Sarah and Jimmy then arrive, each with a bag of jawbreakers, and demand that Jimmy's shampoo be returned. Nazz then enters the lane, wanting to know what the meaning of the note was. Jimmy sniffs her hair and, recognizing the scent, accuses her of stealing his shampoo. The lane breaks into an all-out brawl, and that's when Eddy steps in, telling them that he has the key. He is greeted with derision and a retort that nobody cares. As Eddy watches, befuddled, Edd tells him that the key has indeed unlocked one thing: the paranoia and hostility that festered beneath the surface of the cul-de-sac.
Suddenly, cheers from the fight distract the brawlers. The Kankers have shown up, and they're none too happy about having been denied entry into a neighborhood brawl. When the kids scatter, the Eds are left to face the Kankers. Eddy quickly hides the key behind his back, and when Lee notices he's hiding something, Eddy quickly jams it into Ed's mouth. The Eds then make a break for it, but Ed is slowed down by Jonny, and the Kankers tackle him. Jonny goes flying, landing in Eddy's arms, and both he and Edd look back as the Kankers proceed to try and beat Ed's swallowed loot out of him. Ed eventually throws up a sink, out of which falls the key. Lee picks it up, but Eddy gets an idea, and he throws Jonny at Lee in a "trade". Jonny lands on Lee, and the key goes flying; Eddy picks it up, and the Eds run for it. Lee gets Marie and May to get Jonny off of her, and they give chase. The Eds make it to Ed's house, but are stopped by a locked door. In a panic, Edd and Eddy inform Ed of the dire emergency, only for Ed to declare nonchalantly that he has a key. Ed puts his hand in his pocket and finds a hole, which leads him to suggest that his key fell out of his pants. Hearing this, Edd and Eddy swiftly realize the key they've been carrying around this whole time belongs to Ed. Eddy desperately tries to get the key in the lock, but by now it's too late; the Kankers have found the Eds and proceed to capture them.
Having captured them and trapped them in Ed's basement, the Kankers put the key to good use by locking the boys' feet in stocks made from the door. They then unclothe their feet, and Edd and Eddy swiftly realize what's about to happen. Edd and Eddy cry for mercy as the Kankers' place the soles of their feet against those of their chosen boyfriends, giving them footsies, which Edd and Eddy deem disgusting while Ed deems May's feet to be clammy.
While under the effects of Edd's soda, Ed crashes into a wooden fence. Upon impact, the fence was white. Moments later, the fence is shown to be brown.
Ed damages the ground and creates a mess after his soda induced flight ends. When Ed stands up, the mess is gone.
Eddy breaks the fourth wall when he catches Jonny and says "Does this guy sleep through the whole show?"