In the episode "Fa-La-La-La-Ed", Ed mistakenly thinks it's Christmas and puts up a mistletoe. When Edd and Eddy accidentally walk under it together with him, Ed is all too willing to kiss them (also note how neither of them seem squicked out by this).
And to add onto this, Edd's only reaction was this, and I quote:
"Ed, please! Someone may be watching!"
A bit later in the episode, when Eddy spends all the money he earned while christmas caroling once everyone began to have fun with the idea of an early Christmas, he digs into the bag of jawbreakers he bought and the first one he pulled out, he had meant to give to Double D, only for Ed to steal it away and hand out all of the jawbreakers to the kids in the cul-de-sac, leaving absolutely none for him and his two companions.
Near the very beginning of the same episode, there is a bit of a JimmyxEdd moment when Jimmy offers his full piggy bank to him as a christmas present and as Sarah pulls him away before Eddy could take the present instead, Edd is seen with folded hands and staring rather dreamily in the direction he exited. Granted, he had openly stated that he was happy that the kids of the cul-de-sac, given the feeling of Christmas, realized it was better to give than to recieve.
In the episode 'May I Have This Ed', Eddy learns about a school dance and puts up a poster claiming whoever signs it can 'Win a Date with Eddy'. The only person who signs it is Ed, who in turn blushes bashfully.
Also in that episode, after a chaotic evening at the school dance Eddy proclaims: "I'm done with dames!". Note Double D's reaction◊.
On Edd's defense, he was dancing with Nazz before the chaos ensures, causing Marie to get jealous. Yet, still note that the smile only appeared for a literal second the moment he said it and disappeared not long after.
Some of the Ho Yay comes from Ed's innocently naughty remarks.
There's also the movie in which Edd has a bit of No Sense of Personal Space towards Eddy, Eddy's brother remarks how Edd is Eddy's girlfriend (note how neither Edd nor Eddy deny what he'd said), and Ed asks Eddy for a goodnight kiss.
Eddy was going to deny it in the original draft, he bursts out laughing and shoves Double D at Ed, but it slowed things down.
Also in the movie, Edd and Eddy have what feels a whole lot like a lover's quarrel, which ends in Edd turning and leaving Ed and Eddy alone in the swamp. Eddy absolutely falls apart, starts bawling, and screams an apology at Edd while berating himself to try and get him to come back.
And when Edd does come back, the two of them ride off into a sunset on Ed's shoulders with their arms around each other. And Eddy is still crying, only now they're happy tears.
Before Double D is rudely awakened by the stench of Ed's feet, it appears he and Eddy were sleeping right next to each other. With only the jar of fireflies between them.
In the Valentine's Day episode Edd gives Ed and Eddy Valentine's Day cards (Eddy's says "You electrify me.") and at one point Eddy puckers his lips at Kevin before realizing who it is.
The Valentine is seen again in 'May I Have This Ed', when Eddy's throwing stuff out of his closet. While everything else is lying haphazardly on the floor, the Valentine is carefully propped up against the wall, which shows Eddy places an importance on it. This and the very fact that he kept it is enough to show how much it meant to him.
Let's not forget the end of that particular episode where Ed gives Eddy CPR. Ed: "Mouth to mouth for Eddy!"
Similarly, in "It Came From Outer Ed", Ed gives Jimmy mouth-to-mouth and later tries to do the same to Double D.
"A Fistful of Ed" gave us hints of Edd/Ed and Edd/Jimmy.
And Edd/Eddy. In the conclusion of the episode, the Kankers appear and it is revealed that all three girls knew Double D was just being clumsy and Lee is wearing a cast. The girls, ignoring the other two Eds, attack Double D in kisses. Not long after that comes that line all Edd/Eddy fans have come to love:
Eddy: HEY! HE'S HAD ENOUGH ALREADY!!! So BEAT IT!
Another note: through the entire episode, Eddy is the only one who tries to publicly stick up for Double D. Granted, he DID seek his heart's desire with blackmail, threatening to tell Double D to beat them up if they didn't do what he wanted, claiming he was the "best friend of the school bruiser", but there was no actual reason shown/claimed vocally for him to stick up for Double D at the last moment as he had done.
In later seasons of the show, Jimmy seems to be harboring what can only be described as a girlish crush on Double D, which could mean he wasn't only upset that he was stealing Sarah's attention... in the movie, he makes a point of dusting him off while everyone else is beating the ever loving crap out of Johnny for harming the Eds that they liked now, and he's a bit too happy when Rolf pushes their faces together in "Too Smart for His Own Ed". He does copy everything Sarah does, so it could be an extension of that, but their relationship blatantly borders that of a Fag Hag and Pet Homosexual as the series progresses.
In 'Scrambled Ed', Kevin and Eddy are pulling on Double D...
Kevin: This dork owes me a bike chain!
Eddy: He's MY dork, leggo!
In 'Shoo Ed', Eddy pats Double D's cheek and says, "Just stand there and look pretty!"
In 'Duelin' Eds', Double D says he's going to make cupcakes for Eddy; Eddy's smile of appreciation is seen for a second before Rolf interrupts.
In 'Luck of the Ed':
Ed: Boy, Double D! Eddy never looks at ME like that. Lucky feller.
In 'The Day the Ed Stood Still':
Eddy: *calling to Double D* Hey, useless! Put those rings down and take a load off your eyes. *bats eyelashes*
In 'Little Ed Blue', Double D plays a cavewoman in the movie the Eds make, and Eddy tries to show off his muscles to "her".
After Eddy gets fed up and smacks Ed in frustration, Ed has a HUGE epic freakout, causing Edd to faint. Eddy at first ignores this but is then seen fanning Edd and desperately yelling at him to wake up. Considering how often he shows little to no sympathy at all when his friends get hurt, this definitely is a sweet moment for the two.
Alternatively, he's just trying to wake Double D up because he doesn't want to be the only one dealing with a rampaging Ed.
In 'A Case of Ed', Double D's wearing a hospital gown, under which he has on nothing but underwear, and the gown's open in the back. Eddy says, "Nice shorts, Romeo!" when he passes Double D once.
In this same episode, at the end it is strange that Edd seems to have a spare key to Eddy's door when Kevin is attempting to get in. Though it is also possible that he merely knew the hiding place for said key.
In 'Here's Mud In Your Ed', Eddy begins thinking of what he'll do when he becomes rich. What's the first thing he says he wants to do? Buy Double D a new hat. One would expect greedy Eddy's first thoughts to be of his own self, but they're of Double D. Although, before this, he stated he may buy his father another house.
In 'Tight End Ed', Eddy says to Double D, "I'm only on this stupid team 'cause this uniform makes me look like a hunk!" Then he grins and puts his hands on his hips. Double D's response to this is to start giggling. Seems pretty much like a flirtatious exchange.
In 'Ed Edd n Eddy's Boo Haw Haw', Eddy says to Double D (rather grumpily and as if he were jealous), "Ed this, Ed that. Why don't you marry the guy?" (adding on to this statement, only seconds after does Ed reply, stating that he is "taken")
Why is Double D waiting for Eddy right at the beginning of that? I mean, Ed went home for a movie marathon, but he's still at school for detention to end. Maybe it's just in Double D's good nature, but he does tell Eddy he deserved what he got and still hangs about for him.
Then, we have this line in 'Ed...Pass it On'
Kevin: What's with the balloons; you dorks getting married? To each other?!?!?!?
In the episode 'Ramblin Ed', Edd and Eddy slept together in the same bed.
Eddy: Turn out that light!!
Rolf: Ah, yes!! Sorry Ed-boy!!
In the episode 'Key to My Ed', Ed is dancing around while Rolf is playing music. He dances with Eddy and slams him into Double D, the two catching each other in a dancing position. Double D's only remark is a smirk and, "What? No flowers?"
It's noted that the only two instances of on screen lip-kissing in the series was between two guys.(example: Edd and Eddy kiss in the episode "Your Ed Here")
Rolf pulling out Edd's tongue and kissing it. Granted, he thought Edd was a woman at the time... but only because he was in drag!
In the episode 'A Boy And His Ed', Ed, Edd, and Eddy wound up in Kevin's bath, while he was naked and washing himself. At which point, Eddy wrapped his arm around Kevin's waist and scrubbed his head...or...hat. Granted, it was only to get Jawbreakers.
What, no one's posted THIS YET? Dude, just watch the end, when JIMMY GRINDS ED.
Ed: And sink 'em pants style!
This Troper always though Ed said, "Shake your pants down." But after reading the subtitles on the DVD, it would seem he says, "In syncopated style."
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. Ed has this reaction to it◊.
In one of the early episodes Nazz has a pool party and the Eds decide to show up in speedos. About halfway through the episode the speedos fly off and the Eds spend the rest of the day and night in the pool. The tiny pool. Naked. Right next to each other.
With no sign of being uncomfortable with it.
Jimmy and Johnny occasionally have this, interestingly enough.
Johnny: I can't take my eyes off of Jimmy either, Plank!
And let us not forget how interested Jonny is in Jimmy's injuries. And he's got the rape face to prove it.
In the very beginning of the episode "Truth or Ed", (I will not mark this as a spoiler, for it's only in the very beginning and has practically nothing to do with the main plot) Plank, Johnny, Kevin, Nazz, Rolf, and Ed are all playing basketball on teams (Rolf and Kevin were the team captains, so naturally, Eddy was not picked to be on either team, Rolf even going so far as to select Plank as his final player). When they begin playing, Eddy stands by himself watching the game angrily. It didn't last long, however, since Ed had decided to catch (and manage to pop) the ball with his teeth. As the disappointed former players are leaving (all except Ed), Double D appears out of nowhere at Eddy's side, making googly eyes at him and him alone out of his excitement for the reason that follows.
In the episode "The Eds Are Coming" (the alien invasion special), after the kids rush to check out the supposed asteroid that shot out of Rolf's chimney and crash-landed in the middle of the park and a slimy green hand pops out of it, the kids are frantic and begin to scream and run away from the spot, hiding from plain sight. Eddy runs and hides near Double D, and when they think the cost is clear, they start to walk towards the "asteroid". But they fall short when a figure appears in front of them, at first frightening both of them. They slid backwards and Eddy is seen holding on for dear life to Double D, the same reaction coming from Edd, only Eddy is in front and for a brief second, you can see that Eddy is looking determined and trying to hide Double D behind him, as if he were protecting him.
What makes the above more adorable, perhaps, is that Eddy is actually CARRYING Edd rather than walking with him.
Also, later in the episode, Double D and Ed start to run towards the house giving off a terrible heat and oozing eerie green smoke when Eddy grab them and insist they stay, concerned that the "aliens" will suck out their brains, although he is all too willing to go out himself and capture them. If you think about it, it is as if he would risk his life to save them both. And with the subtle hints throughout the entire episode with Edd and Eddy, it would seem as though he were more concerned about Double D.
But you forget that they are friends. It is normal being worried, whether or not Ho Yay.
But you are forgetting that this is Eddy we're talking about, who has shown throughout most of the series to only care about himself. Concern for Double D is definitely Ho Yay.
Let's not forget how often the male cast is always grabbing each other's bottoms, especially Eddy with Ed in "Too Smart For His Own Ed."
In Jimmy's dream in "The Eds Are Coming", Kevin was shirtless.
In "They Call Him Mr. Ed", Rolf pulls Kevin by the butt.
In the title sequence, Eddy's nudging Double D and waggling his eyebrows at him. Heck, he lands on him when Ed throws them out of the way, and if you pause it at the right moment, Double D is smiling dreamily.
In "Shoo Ed," Rolf is very interested in Jonny's annoyance.
Eddy: What just happened? Rolf fell in love with the guy!
In the episode, "Once upon an Ed." (Season 3 Episode 4), Ed's story has Edd clinging onto him constantly as they are chased by the mutant Kanker sisters. This could be interpreted as Ed's usual habit of helping a constantly distressed Edd, but one can't help but wonder why Ed would chose on having Edd more distressed/clingy that usual.
In "For Your Ed Only", in order to blow a bubble for an escape route from Sarah's wrath, Ed impatiently gives Edd a form of mouth-to-mouth. Causing Edd's hat to inflate into a bubble. Edd's only response is "I have Ed germs!" Rather than "What The Heck!?"
Of course this could also be seen as a desperate move from Ed, seeing how Sarah was going to beat the living daylights out of them.
This scene from "Momma's Little Ed"
Edd: [hugging Eddy] Thank you, Eddy! Thank you! You won't even know I was there!
Eddy: [uncomfortable] Uh, our faces are touching, Double D.