The entire series is laden with homoeroticism. Putting aside the obvious "little boy in a silly pink hat has colorful adventures with two magical fairies" side of the series, we see that Fairly Odd Parents practically radiates homoeroticism. Men are consistently sexualized, being called hot, hunky, gorgeous, handsome, ripped, etc, while the women, who are almost completely ignored by the men, all have Hartman Hips.
Cosmo frequently has fan girl moments towards good looking men.
However, the most direct and obvious example of Ho Yay! has to be between Sanjay and Timmy. Sanjay is a 10-year-old Indian (Hindu) boy who is somewhat obsessed with Timmy. Sanjay is Timmy's third best friend and considered a "back up friend" when Chester and AJ are not available. In episode "Escape From Unwish Island". Sanjay expressed his happiness that Timmy came to rescue him, along with others who were trapped in a cage. To explain the odd reason of why Timmy was shooting lasers out of his eyes to melt the cage bars, Timmy explains that everyone is dreaming.
Timmy: Yeah, and, uh, this isn't real and you guys are all in a dream. (uses heat vision to free them) Sanjay: And I'm having one of those dreams where Timmy saves me again - but where is your white horse?
Timmy: Now go home, go to bed. When you wake up, you'll all be normal. Sanjay: See you in my next dream. Timmy: Go!!!
There have been many more eyebrow raising moments when it came to Sanjay and his open admiration for Timmy Turner.
As seen in SE7 "Stupid Cupid" where Sanjay's date is Kimmy... a visual gender swapped version of Timmy.
From Trixie's end of it, "The Boy Who Would Be Queen" has her say "That's what I have girlfriends for." Granted, she probably didn't mean it that way, (she was just saying it as an excuse to get out of talking with Timmy), but when combined with Veronica's example above... yeah.
That episode features Gender Bender fun for Timmy and co, and led many fans to believe Trixie had a thing for "Timantha". The line "If you were a boy, I would totally date you" (or something to that effect) was a big part of it.
The Jimmy/Timmy Power Hour Three is either this or a Plot Hole. There is no explanation for the events of the episode than this. There is no explanation except homosexual attraction for why Jimmy Neutron and Timmy Turner, who spent an entire double length episode fighting with one another, suddenly go from enemies to friends in three lines.
Cupid and Juandissimo. "Maybe you should have a salad."
Also, Mark Chang, who might have a crush on Vicky but seems to hug Timmy an awful lot. And Wishology had them the only ones who can save the world. "Nice man smooch" indeed
Also, Adam West falls in love with Mr. Turner in drag
Mr. Turner and Cosmo have both had a man crush on Chip Skylark.
In the episode "Love at First Height", Timmy wishes himself to be a 16-year-old supermodel named Gah in an attempt to be tall enough to ride the Heart Stopper. Frequently throughout the episode, all the characters, both male and female characters in the show are unusually excited when he is mentioned, especially the adults. They also utter the phrase "He's Norweigalicious.." Also, when Chester and AJ get dolls of Gah, they sighs lovingly at the doll and faint.
In "Just the Two of Us", Chester dresses up like a girl when he and AJ need skating partners. And before they skate he tells AJ "You better call me after this." It was also hinted that the two play a couple regularly when partnering is required.
AJ:(to Timmy, in Trixie's voice) Tell me I'm pretty.
Upon seeing Mr. Turner in a speedo, Dinkleberg remarks "Hey, looking good Turner!"
The Ho Yay in this show spills over into the nameless one-shot filler characters too. In "Channel Chasers" there are a pair of cops who meet in an alley with coffee and donuts. They then sit on a dumpster to discuss life. And then they scooch closer together.
"Remy Rides Again" is filled to the brim with Remy/Timmy Ho Yay. Remy gets down in his knees in the first scene a la a marriage proposal, and any attempts at subtlety subsequently croaked.
Doubles as Foe Yay is Anti-Cosmo, who planned on making Timmy his scary godchild with short shorts.
The apple doesn't fall too far from the tree, it seems; Foop has a considerable amount of Foe Yay with his counterpart Poof. In one episode, their teacher paired them up for a Egg Sitting assignment and everyone treated the two of them like a married couple. And they acted like one too.