When both Ed and Edd's attempts to play tricks on Eddybackfire, he ends up getting a very fat head and openly declares himself as the King of the Pranksters, claiming that before the day is out he will have made every kid in the Cul-de-Sac his victim.
But out of the blue comes a shock for Eddy's ego in the shape of the enigmatic Prank Master who is slowly working his or her way through the neighborhood. Rolf is tossed into the mud in a butter churn barrel, Jonny 2x4dangles from a tree in a diaper, Kevin gets nipped in a bear trap, Sarah falls into a trap door, and Jimmy gets pranked with a silly-face balloon in a present. Kids everywhere are tripped, squashed, trapped and generally embarrassed and as soon as the Eds dive for the sandbox, a bunch of Prank Master cards surround them completely. Edd realizes they are next since the Prank Master has gotten everybody else. Eddy's confidence seems to have evaporated and it's only a matter of time before the three quivering panicking Eds meet their nemesis so they have to be ultra cautious for anything that appears somewhat suspicious. After finding ajawbreaker that appears out of the blue and just stands there, Eddy believes it may be a trap, but he may be wrong since nothing has happened yet. They slowly approach it and Eddy then taps it before he nudges it away two times with his hockey stick, but still nothing happens yet.
Sarah and Jimmy are then shown walking down the sidewalk and they notice the jawbreaker. Jimmy takes it and begins to lick on it a bit before sucking it into his mouth, and then they walk away. Eddy realizes he was wrong about the jawbreaker. Embarrassed, he quickly changes the subject by tying Edd's hat to his underwear, then Ed gives Eddy a wedgie, and Edd and Eddy pulls Ed's pants up to his armpits. Suddenly, they see all the kids laughing at them in a nearby bush. They reveal there was never a Prank Master and that they all pretended to be pranked. Eddy, refusing to give up his title as The King of Pranks, plans to get them all back for that. The Eds leave to make a new plan on getting back at the kids.
While the other kids are playing around the Cul-de-Sac, the Eds plan a super prank in Eddy's garage. It's called the El Mongo Stink Bomb. Eddy explains to his friends that his Older Brother taught him how to make it before he left. Eddy then puts the last finishing touch to the bomb by placing Ed's stinky sock into the bomb. As they finish it, they try to get it out of the garage but it gets stuck. As they try to get it out, it suddenly explodes, spreading from the garage to all over Peach Creek and blowing a massive wave of stinky gas at everyone's faces. In the end, everyone has been pranked, including the Eds themselves. Eddy faints from the smell(but not before saying "Yes! I stink, therefore I am!"), Edd can't stand the stench, and Ed doesn't mind the smell, claiming that it smells good.