"Know it All Ed" is the 1st episode of Season 2 and the 27th episode of Ed, Edd n Eddy. In this episode, the Eds discover a box of "Canadian Squirt Guns" and sell the squirt guns for 50 cents each to the kids. Eventually everyone starts acting like they are in the Old West.
The Eds are playing around at the junkyard and generally having a good time when a chance tumble lands a box full of turkey basters in front of them. Edd recognizes these for what they are, but Ed and Eddy have different takes on the situation entirely, with Ed thinking that they're alien exploratory probes dropped off to conserve fuel during a mutiny of pulsating brain mutants and Eddy believing them to be Canadian squirt guns. Edd is doubtful, so Eddy fills one up and demonstrates its "proper" usage, and seeing this, Ed joins in. Delighted with this response, Eddy comes up with an idea: he and his friends will market the squirt guns to the kids of the cul-de-sac.
Thus the Eds find their way to the lane, where the kids are playing in a makeshift bowling alley. Eddy demonstrates the gun, showing off its power and accuracy, and all the kids are impressed. The advertising nearly done, all Eddy has to do is direct the kids to the sales counter at Double D's House of Import-Exports. When Eddy does this, the kids stampede the counter and pick up guns, along the way filling Eddy's money jar halfway full with quarters. Seeing this, Eddy realizes that today is his lucky day, and that they've got to keep the gravy train rolling.
To further this end, Eddy becomes "Marshall Eddy" and Edd "Double Deputy D". They then proceed to wander around the cul-de-sac, ticketing the cowpokes for the most minor offenses; Kevin gets a ticket for hitching his horse in a no-hitching zone, Rolf has to pay a fee for prospecting, Jimmy gets slapped with a railroad tax due to his retainer, and Sarah is fined for disturbing the peace when she yells at Eddy. Fed up, they declare that they won't pay their fines, and Eddy is at a loss for what to do when Jonny and Plank's runaway wagon bounds through the lane and crashes into a tree. Jonny topples out, tied up, and says that they were set upon by something evil that sprayed them with perfume. Eddy suggests that maybe the kids should have paid their fees, and the kids quickly cough up some cash to cover it. Eddy is happy until his jar is ripped from his hands by Lee. He reaches into his pockets and finds that his squirt guns have been stolen. The Kanker sisters have arrived, and they are the outlaws who plagued Jonny and Plank. When the defenseless Eds make a break for it, the Kankers lasso them and spray them with perfume before leaving, happy with their haul.
Eddy swears revenge, however, and soon the Eds set out to get it. Along the way, they pass three grave-like holes in the ground, suggesting that the community hasn't much faith in them. Despite this, Eddy leads them onwards, and they make it to the construction site, where the Kankers are waiting for them.
What follows is an epic battle where the Eds do their best to defeat their nemesis. This includes novel techniques such as Ed firing five guns at once and Edd using a makeshift machine gun to fire at the Kankers. When the dust clears and the water stops flying, however, the Eds realize that they missed every shot, as the Kankers are still standing in front of them, dry and safe. The Eds are scared, as the Kankers ready their guns and fire. When the firing stops, however, Eddy realizes that the Kankers only hit their feet. Unfortunately, the guns were loaded with the Kankers' own brand of rubber cement, and the Kankers are going to do some "home cooking" with the Eds. Lipstick will be involved.
Eddy: [atop a pile of garbage] "I'm the king of the castle and you're a dirty-" Ed and Edd: [jumping on Eddy] "Dogpile!"
Eddy: [seeing Ed try to make sounds out of the giant tube] "Boy, Double D, you stink. Let a pro show you." Edd: "Certainly, Eddy." Eddy: "It's all in the technique, Sockhead. Pure talent." [He tries to make a sound through the tube, but he screws up.] "Wrong technique. Slight adjustment and…" [He tries it again, but Ed blows into the tube, making an inflatable Eddy.] Ed: "I am a whale, Eddy. An endangered mammal. Hug me."
Edd: "Help." [Eddy takes the jar of money from Edd.] Eddy: "Whoa, Nelly! They fell for it. Oh, today must be my lucky day. Come on, boys, let's keep this gravy train rolling." Edd: [with the fake moose head on his head] "Coming Eddy." [Edd falls on the ground, still wearing the fake moose head.] Ed: "I was a moose once."
Ed: [looking at the turkey basters] "Oh look! A whole box of alien exploratory probes, dropped off in an attempt to save fuel during a mutiny of pulsing brain mutants." Eddy: [looking at Ed with surprise] "I think that eyebrow's too heavy for his head."
Eddy: "What we have here is a squirt gun!" Edd: [doubtful of Eddy's idea] "Puhlease! A squirt gun?" Eddy: "What? Yeah! A Canadian squirt gun!" Ed: [with Canadian squirt guns stuck to his face] "Canadians are weird!"
Edd: [freaking out with his powerful weapon] "Oh, I feel it! I feel the adrenaline, Eddy baby!" Eddy: "Double D! Double D! Relax, will ya? It’s a toy - from Canada - geez, how embarrassing."
Ed: [appreciatively sniffing the perfumed Plank] "Plank reminds me of fresh cut spring flowers spewed across a babbling brook with a hint of lemon."
Eddy: "Attack the lump!" [Eddy jumps on top of Ed, covering his eyes.] Ed: "Oh no, something ate my head!"
Eddy: "That's a 25 cent prospecting fine!" Rolf: "But I am washing dishes, no brain Ed-boy." Eddy: "25 cents or 25 days in the pokey!" Edd: "Ahem, wrong cartoon, Eddy."
[The Eds are hiding behind a sign at the construction site before calling out the Kankers for a duel.] Edd: "This is desperate Eddy. What if... we're captured and forced to clean their gutters!?" Ed: "I don't know what a gutter is Eddy!" Eddy: "You'll be living in one if you don't COME ON!"
When the squirt gun stand fell apart, the writing on the 50 cents sign turned red for a second.
The Kankers had purple perfume in the Eds' squirt guns, but when Lee said "And who's gonna help him?" they are shown to contain water. After that, when the Kankers are about to squirt the Eds, they have orange liquid in their squirt guns.
After the Kankers spray the Eds with the Krankshaft perfume, the squirt guns reappear on the Eds.
Starting with this episode and for the rest of the series, Eddy's tongue color is now green, as his tongue was previously yellow.
The Canadian Squirt Gun is seen again in "The Good Ol' Ed." It even still has water in it.
When Eddy was demonstrating how to use the gun on Ed, we can clearly see Ed being as thin as cardboard when he turns after being shot. However, during the final shot, which pans across the characters as the water shoots through their ears, thus rendering Ed off-screen for the duriation of the scene, Ed is 3D when the camera returns to him and he gets hit.
Subsequently, during the duration of cardboard Ed, his hair is replaced by a spiky scalp. This may have inspired his design for "The Incredible Shrinking Day."
This is the second episode in which the Kankers give a makeover to one or some of the characters. This happened for the first time in "Quick Shot Ed" and this happens again for the third time in "Ed Overboard." The first time this happened was to the Eds, this time it was Plank and Jonny and the third time it happened, the makeover was done to the Urban Rangers and Ed.