In the episode "Flea-Bitten Ed" the boys take care of Rolf's animals including two rabbits and Ed accidentally leaves the two alone together. By the end of the episode, there are so many bunnies that they flood the street. The sight causes Double D to say:
Double D: It seems like Mr. and Mrs. Bunny have been practicing the multiplication table....
Edd is the least masculine person in the entire cast (sans Jimmy). His nickname? Double D!
In "Home Cooked Eds", the Kanker Sisters invade Eddy's house while on vacation, and at one point a terrified Edd says something along the lines of, "I fear they're becoming amorous..." He then whispers the meaning into a confused Eddy's ear, and the Eds quickly flee the house, screaming in terror. (To those who simply are too lazy to open a dictionary, to become amorous means you're getting ready for sex.)
And before you ask, no. There's not another definition or connotation for it, so it really means what it means.
It doesn't help that they were trying to put him in skin tight leopard skin underwear beforehand.
Later, when Eddy and Kevin are trying to push the trailer to each other's side of the fence, the Kankers mention it feels like the vacation their mom took. Considering the things said about her character, it could give disturbing images.
Not as bad as you might think, since Lee did explicitly say that said vacation was a cruise.
We also got this from "Who, What, Where, Ed":
Eddy: [dressed in a pimp-like tuxedo] I'm doing a survey and... Lee: Our mom's not home.
To be fair, that's a pretty standard response for a kid to give if someone says that they're doing a survey, so YMMV if that was on the Radar or not.
But then again, in the very first episode with them, we learn that the Kanker sisters all have different fathers.
Pretty much every scene ever involving Jimmy, whose sexuality has been called into question several times. Just look at the page picture!
The episode where Eddy's mom is cleaning the house and he asks Ed to hide his magazines is one 11 minute long giant middle finger to the radar. At one point he says that his (older) brother gave him the magazines, at another he thinks Ed hid them in a sewer and Edd mentions that the smudge would render them unreadable. Eddy's reply? "It's the PICTURES I'm worried about!"
Also, there was this:
Eddy: I'd tell you I love ya, Ed, but I ain't that kind of guy!
The sound effect that plays when Eddy says "viewing pleasure" counts as well.
And when Eddy says he's hiding his... "magazines" to Double D, he sounds a bit more discreet than you'd think he'd be, and Double D sure had one heck of a naughty face.
In the episode "Hand Me Down Ed", a mysterious boomerang causes some of the kids' personalities to change hilariously. When Ed holds it, it he becomes a TV Genius. When Eddy holds it, he becomes maternal. But when Double D holds it? He becomes a stripper. note And true to the trope, the hat was the only thing that stayed on him at the end of the episode.
For consideration, he sounded like a beatnik or a hippie, so maybe it was a nudist and not a stripper. But the point still stands, whatever the case, that he gains a compulsion to strip naked.
In "1 + 1 = Ed", Ed saws a circle into the sky and sees the Kanker sisters having a bubble bath. Afterwards, Eddy snickers and asks him "Did you see anything?".
There's one where Eddy decides to take apart an old wardrobe to "learn what's inside". He finds a bra.
In Robbin Ed, Eddy begins a costume change to confront Captain Melonhead/Johnny, and throws off his underwear and a pair of fuzzy dice. Think about that for a second. What could someone with an inferiority complex possibly be using a pair of fuzzy dice for?
In "Rent-a-Ed" after breaking a pipe in Johnny's house while trying to fix it up the Eds decide to convert it into a sauna, Rolf really enjoys it when suddenly his towel blows off revealing he's not wearing anything underneath, everyone reacts in shock or disgust except for Jimmy who curiously says "Ooh!"
When Ed wakes the other two Eds up early because he thinks it's a school day in "Cleanliness is Next to Edness", Eddy angrily throws him out of his bedroom. When Ed pops up at the window and complains, Eddy tapes one of his magazines to the window. Ed's grin says it all.
Everything about the Kanker sisters' warped romantic pursuit of the Ed boys is pretty much what Moral Guardians would consider Black Comedy Rape (albeit a kids' show version of it).
Looking closely at one of the sticky notes on Edd's bathroom wall reveal the words "Don't touch yourself".
The infamous sextant scene from the movie. Apparently since it was the finale, the writers decided they could do whatever they wanted.
In similar cases, don't forget this scene from "Look Before You Ed".
Coming back to the Kanker Sisters, their name might be a nod to chancre sores (which is spelled pretty similar to canker sores, something noncontagious), which are a type of oral ulcer which appear very similar to genital herpes sores. In fact, genital herpes sores and chancre sores are related, in that they're from the same virus, and it is possible to give someone genital herpes if you have chancre sores in your mouth.
At the beginning of "Pop Goes the Ed," Ed and Double D attack a beehive with bats while Eddy hangs back to avoid being stung. The bees, needless to say, chase the boys down the road. Eddy makes it into his house and locks the door, Ed and Double D do not, and while they are being stung outside of the house, there is an audible, "OW, FUCK!" from Double D.
Often when Eddy is in trouble with the Kanker sisters - especially when they drag him off to kiss him - you can hear him shout "I'm a minor, stop!"
From "Out With the Old, In With the Ed", when Edd is sent rolling down the stairs in order to talk to the Kankers about switching homerooms. Keep in mind that Edd lands on his back with his legs stretched out rather far.
May: "It's our boy toy, guys!"
Lee: "Check 'im out; he must be good at gymnastics!"
Marie: "Let's find out!"
From "To Sir with Ed", in which Ed was pretending to be a dog while at Edd's house. Keep in mind that we cannot see below Edd's waist in this shot.
Eddy: (on the phone with Edd) Why don't you guys come on over?
Edd: Gosh, Eddy, a tad late, don't you think? I mean, Ed was finally going to-*stops and shivers* Please let go of my leg, Ed...
When Nazz goes to check on Eddy's bath, Double D panics that "she's skipping a chapter [of the dating book they've been consulting]." In other words, she skipped a base.
If you look carefully in the Valentine's Day episode, there is a shot of the inside of May's locker when Lee and Marie open it. Inside she has several photos of Double D...including one of his butt.
The Kanker sisters snicker at an anatomy book.
In the first scene in "Nagged to Ed", Eddy is given a pair of gloves and galoshes to put on. He's then shown intentionally and comically misusing the equipment he was given. What the radar failed to pick up was his left hand◊ (to clarify, Eddy is basically giving the finger).
In the same episode: It's pretty obvious to everyone but the Ed's, that the Kranks wanted certain things in return for their burgers. And how did they end up in bathrobes anyway?
Nazz says this gem of a line to Ed in "Boys Will Be Eds";
Nazz: "Hiya big guy, are you gonna touch me with that ball?"